Merge pull request #24948 from nextcloud/dependabot/composer/doctrine/dbal-3.0.0

Bump doctrine/dbal from 2.12.0 to 3.0.0

109 files changed, 1307 insertions, 852 deletions

diff --git a/.drone.yml b/.drone.yml
index 60c316e3148..8ea80eb76c5 100644
--- a/.drone.yml
+++ b/.drone.yml
@@ -7,7 +7,7 @@ steps:
   commands:
     - git submodule update --init
 - name: checkers
-  image: nextcloudci/php7.3:latest
+  image: nextcloudci/php7.3:php7.3-5
   commands:
     - ./autotest-checkers.sh
   secrets: [ github_token ]
@@ -224,12 +224,12 @@ steps:
   commands:
     - git submodule update --init
 - name: nodb-php7.3
-  image: nextcloudci/php7.3:latest
+  image: nextcloudci/php7.3:php7.3-5
   commands:
     - bash tests/drone-run-php-tests.sh || exit 0
     - NOCOVERAGE=true TEST_SELECTION=NODB ./autotest.sh sqlite
 - name: nodb-php7.4
-  image: nextcloudci/php7.4:latest
+  image: nextcloudci/php7.4:php7.4-3
   commands:
     - bash tests/drone-run-php-tests.sh || exit 0
     - NOCOVERAGE=true TEST_SELECTION=NODB ./autotest.sh sqlite
@@ -261,12 +261,12 @@ steps:
   commands:
     - git submodule update --init
 - name: sqlite-php7.3
-  image: nextcloudci/php7.3:latest
+  image: nextcloudci/php7.3:php7.3-5
   commands:
     - bash tests/drone-run-php-tests.sh || exit 0
     - NOCOVERAGE=true TEST_SELECTION=DB ./autotest.sh sqlite
 - name: sqlite-php7.4
-  image: nextcloudci/php7.4:latest
+  image: nextcloudci/php7.4:php7.4-3
   commands:
     - bash tests/drone-run-php-tests.sh || exit 0
     - NOCOVERAGE=true TEST_SELECTION=DB ./autotest.sh sqlite
@@ -298,7 +298,7 @@ steps:
   commands:
     - git submodule update --init
 - name: mariadb10.1-php7.3
-  image: nextcloudci/php7.3:latest
+  image: nextcloudci/php7.3:php7.3-5
   commands:
     - bash tests/drone-run-php-tests.sh || exit 0
     - NOCOVERAGE=true TEST_SELECTION=DB ./autotest.sh mariadb
@@ -334,7 +334,7 @@ steps:
   commands:
     - git submodule update --init
 - name: mariadb10.2-php7.3
-  image: nextcloudci/php7.3:latest
+  image: nextcloudci/php7.3:php7.3-5
   commands:
     - bash tests/drone-run-php-tests.sh || exit 0
     - NOCOVERAGE=true TEST_SELECTION=DB ./autotest.sh mariadb
@@ -369,7 +369,7 @@ steps:
   commands:
     - git submodule update --init
 - name: mariadb10.3-php7.3
-  image: nextcloudci/php7.3:latest
+  image: nextcloudci/php7.3:php7.3-5
   commands:
     - bash tests/drone-run-php-tests.sh || exit 0
     - NOCOVERAGE=true TEST_SELECTION=DB ./autotest.sh mariadb
@@ -405,7 +405,7 @@ steps:
   commands:
     - git submodule update --init
 - name: mariadb10.4-php7.4
-  image: nextcloudci/php7.4:latest
+  image: nextcloudci/php7.4:php7.4-3
   commands:
     - bash tests/drone-run-php-tests.sh || exit 0
     - NOCOVERAGE=true TEST_SELECTION=DB ./autotest.sh mariadb
@@ -446,7 +446,7 @@ steps:
   commands:
     - git submodule update --init
 - name: mysql-php7.4
-  image: nextcloudci/php7.4:latest
+  image: nextcloudci/php7.4:php7.4-3
   commands:
     - bash tests/drone-run-php-tests.sh || exit 0
     - NOCOVERAGE=true TEST_SELECTION=DB ./autotest.sh mysql
@@ -483,7 +483,7 @@ steps:
   commands:
     - git submodule update --init
 - name: postgres-php7.3
-  image: nextcloudci/php7.3:php7.3-4
+  image: nextcloudci/php7.3:php7.3-5
   commands:
     - bash tests/drone-run-php-tests.sh || exit 0
     - sleep 10 # gives the database enough time to initialize
@@ -519,7 +519,7 @@ steps:
   commands:
     - git submodule update --init
 - name: postgres-php7.3
-  image: nextcloudci/php7.3:latest
+  image: nextcloudci/php7.3:php7.3-5
   commands:
     - bash tests/drone-run-php-tests.sh || exit 0
     - sleep 10 # gives the database enough time to initialize
@@ -554,7 +554,7 @@ steps:
   commands:
     - git submodule update --init
 - name: postgres-php7.4
-  image: nextcloudci/php7.4:latest
+  image: nextcloudci/php7.4:php7.4-3
   commands:
     - bash tests/drone-run-php-tests.sh || exit 0
     - sleep 10 # gives the database enough time to initialize
@@ -590,7 +590,7 @@ steps:
   commands:
     - git submodule update --init
 - name: postgres-php7.4
-  image: nextcloudci/php7.4:latest
+  image: nextcloudci/php7.4:php7.4-3
   commands:
     - bash tests/drone-run-php-tests.sh || exit 0
     - sleep 10 # gives the database enough time to initialize
@@ -626,7 +626,7 @@ steps:
   commands:
     - git submodule update --init
 - name: postgres-php7.4
-  image: nextcloudci/php7.4:latest
+  image: nextcloudci/php7.4:php7.4-3
   commands:
     - bash tests/drone-run-php-tests.sh || exit 0
     - sleep 10 # gives the database enough time to initialize
@@ -662,7 +662,7 @@ steps:
   commands:
     - git submodule update --init
 - name: mysqlmb4-php7.4
-  image: nextcloudci/php7.4:latest
+  image: nextcloudci/php7.4:php7.4-3
   commands:
     - bash tests/drone-run-php-tests.sh || exit 0
     - NOCOVERAGE=true TEST_SELECTION=DB ./autotest.sh mysqlmb4
@@ -703,7 +703,7 @@ steps:
   commands:
     - git submodule update --init
 - name: mysqlmb4-php7.3
-  image: nextcloudci/php7.3:php7.3-4
+  image: nextcloudci/php7.3:php7.3-5
   commands:
     - bash tests/drone-run-php-tests.sh || exit 0
     - NOCOVERAGE=true TEST_SELECTION=DB ./autotest.sh mysqlmb4
@@ -2008,7 +2008,7 @@ steps:
   commands:
     - git submodule update --init
 - name: nodb-codecov
-  image: nextcloudci/php7.4:latest
+  image: nextcloudci/php7.4:php7.4-3
   environment:
       CODECOV_TOKEN:
           from_secret: CODECOV_TOKEN
@@ -2039,7 +2039,7 @@ steps:
   commands:
     - git submodule update --init
 - name: db-codecov
-  image: nextcloudci/php7.4:latest
+  image: nextcloudci/php7.4:php7.4-3
   environment:
       CODECOV_TOKEN:
           from_secret: CODECOV_TOKEN
@@ -2070,7 +2070,7 @@ steps:
   commands:
     - git submodule update --init
 - name: object-store
-  image: nextcloudci/php7.4:latest
+  image: nextcloudci/php7.4:php7.4-3
   environment:
       CODECOV_TOKEN:
           from_secret: CODECOV_TOKEN
@@ -2103,7 +2103,7 @@ steps:
   commands:
     - git submodule update --init
 - name: object-store
-  image: nextcloudci/php7.4:latest
+  image: nextcloudci/php7.4:php7.4-3
   environment:
       CODECOV_TOKEN:
           from_secret: CODECOV_TOKEN
@@ -2237,7 +2237,7 @@ trigger:
 #  commands:
 #    - git submodule update --init
 #- name: memcache-redis-cluster
-#  image: nextcloudci/php7.3:latest
+#  image: nextcloudci/php7.3:php7.3-5
 #  commands:
 #    - phpenmod xdebug
 #    - sleep 20
diff --git a/3rdparty b/3rdparty
-Subproject 86573beb84cf3b62b6d01ee377225df83b7d245
+Subproject 09596e43fba86a3643879595a8fb6fece4af6a7
diff --git a/apps/contactsinteraction/lib/Db/CardSearchDao.php b/apps/contactsinteraction/lib/Db/CardSearchDao.php
index 0636829272b..8686183d182 100644
--- a/apps/contactsinteraction/lib/Db/CardSearchDao.php
+++ b/apps/contactsinteraction/lib/Db/CardSearchDao.php
@@ -82,7 +82,7 @@ class CardSearchDao {
 			->setMaxResults(1);
 		$result = $cardQuery->execute();
 		/** @var string|resource|false $card */
-		$card = $result->fetchColumn(0);
+		$card = $result->fetchOne();
 
 		if ($card === false) {
 			return null;
diff --git a/apps/dav/lib/BackgroundJob/UpdateCalendarResourcesRoomsBackgroundJob.php b/apps/dav/lib/BackgroundJob/UpdateCalendarResourcesRoomsBackgroundJob.php
index 5a321779408..e394890e0eb 100644
--- a/apps/dav/lib/BackgroundJob/UpdateCalendarResourcesRoomsBackgroundJob.php
+++ b/apps/dav/lib/BackgroundJob/UpdateCalendarResourcesRoomsBackgroundJob.php
@@ -401,7 +401,7 @@ class UpdateCalendarResourcesRoomsBackgroundJob extends TimedJob {
 
 		return array_map(function ($row) {
 			return $row['resource_id'];
-		}, $stmt->fetchAll(\PDO::FETCH_NAMED));
+		}, $stmt->fetchAll());
 	}
 
 	/**
@@ -435,6 +435,6 @@ class UpdateCalendarResourcesRoomsBackgroundJob extends TimedJob {
 			->andWhere($query->expr()->eq('resource_id', $query->createNamedParameter($resourceId)));
 		$stmt = $query->execute();
 
-		return $stmt->fetch(\PDO::FETCH_NAMED)['id'];
+		return $stmt->fetch()['id'];
 	}
 }
diff --git a/apps/dav/lib/CalDAV/CalDavBackend.php b/apps/dav/lib/CalDAV/CalDavBackend.php
index 178affc46bf..ea1a30c629e 100644
--- a/apps/dav/lib/CalDAV/CalDavBackend.php
+++ b/apps/dav/lib/CalDAV/CalDavBackend.php
@@ -256,7 +256,7 @@ class CalDavBackend extends AbstractBackend implements SyncSupport, Subscription
 		}
 
 		$result = $query->execute();
-		$column = (int)$result->fetchColumn();
+		$column = (int)$result->fetchOne();
 		$result->closeCursor();
 		return $column;
 	}
@@ -1114,7 +1114,7 @@ class CalDavBackend extends AbstractBackend implements SyncSupport, Subscription
 			->andWhere($q->expr()->eq('calendartype', $q->createNamedParameter($calendarType)));
 
 		$result = $q->execute();
-		$count = (int) $result->fetchColumn();
+		$count = (int) $result->fetchOne();
 		$result->closeCursor();
 
 		if ($count !== 0) {
@@ -1963,7 +1963,7 @@ class CalDavBackend extends AbstractBackend implements SyncSupport, Subscription
 		// Current synctoken
 		$stmt = $this->db->prepare('SELECT `synctoken` FROM `*PREFIX*calendars` WHERE `id` = ?');
 		$stmt->execute([ $calendarId ]);
-		$currentToken = $stmt->fetchColumn(0);
+		$currentToken = $stmt->fetchOne();
 
 		if (is_null($currentToken)) {
 			return null;
@@ -2373,7 +2373,7 @@ class CalDavBackend extends AbstractBackend implements SyncSupport, Subscription
 			->from($table)
 			->where($query->expr()->eq('id', $query->createNamedParameter($calendarId)));
 		$result = $query->execute();
-		$syncToken = (int)$result->fetchColumn();
+		$syncToken = (int)$result->fetchOne();
 		$result->closeCursor();
 
 		$query = $this->db->getQueryBuilder();
diff --git a/apps/dav/lib/CardDAV/CardDavBackend.php b/apps/dav/lib/CardDAV/CardDavBackend.php
index c95f6b072e9..d5c36096956 100644
--- a/apps/dav/lib/CardDAV/CardDavBackend.php
+++ b/apps/dav/lib/CardDAV/CardDavBackend.php
@@ -140,7 +140,7 @@ class CardDavBackend implements BackendInterface, SyncSupport {
 			->where($query->expr()->eq('principaluri', $query->createNamedParameter($principalUri)));
 
 		$result = $query->execute();
-		$column = (int) $result->fetchColumn();
+		$column = (int) $result->fetchOne();
 		$result->closeCursor();
 		return $column;
 	}
@@ -661,7 +661,7 @@ class CardDavBackend implements BackendInterface, SyncSupport {
 			->andWhere($q->expr()->eq('uid', $q->createNamedParameter($uid)))
 			->setMaxResults(1);
 		$result = $q->execute();
-		$count = (bool)$result->fetchColumn();
+		$count = (bool)$result->fetchOne();
 		$result->closeCursor();
 		if ($count) {
 			throw new \Sabre\DAV\Exception\BadRequest('VCard object with uid already exists in this addressbook collection.');
@@ -864,7 +864,7 @@ class CardDavBackend implements BackendInterface, SyncSupport {
 		// Current synctoken
 		$stmt = $this->db->prepare('SELECT `synctoken` FROM `*PREFIX*addressbooks` WHERE `id` = ?');
 		$stmt->execute([$addressBookId]);
-		$currentToken = $stmt->fetchColumn(0);
+		$currentToken = $stmt->fetchOne();
 
 		if (is_null($currentToken)) {
 			return null;
diff --git a/apps/dav/lib/Migration/BuildCalendarSearchIndex.php b/apps/dav/lib/Migration/BuildCalendarSearchIndex.php
index 7caa53be89c..f731fdf8963 100644
--- a/apps/dav/lib/Migration/BuildCalendarSearchIndex.php
+++ b/apps/dav/lib/Migration/BuildCalendarSearchIndex.php
@@ -77,7 +77,7 @@ class BuildCalendarSearchIndex implements IRepairStep {
 		$query->select($query->createFunction('MAX(' . $query->getColumnName('id') . ')'))
 			->from('calendarobjects');
 		$result = $query->execute();
-		$maxId = (int) $result->fetchColumn();
+		$maxId = (int) $result->fetchOne();
 		$result->closeCursor();
 
 		$output->info('Add background job');
diff --git a/apps/dav/lib/Migration/BuildSocialSearchIndex.php b/apps/dav/lib/Migration/BuildSocialSearchIndex.php
index 44986436882..b7888b423cb 100644
--- a/apps/dav/lib/Migration/BuildSocialSearchIndex.php
+++ b/apps/dav/lib/Migration/BuildSocialSearchIndex.php
@@ -74,8 +74,8 @@ class BuildSocialSearchIndex implements IRepairStep {
 		$query->select($query->func()->max('cardid'))
 			->from('cards_properties')
 			->where($query->expr()->eq('name', $query->createNamedParameter('X-SOCIALPROFILE')));
-		$maxId = (int)$query->execute()->fetchColumn();
-		
+		$maxId = (int)$query->execute()->fetchOne();
+
 		if ($maxId === 0) {
 			return;
 		}
diff --git a/apps/dav/lib/Migration/CalDAVRemoveEmptyValue.php b/apps/dav/lib/Migration/CalDAVRemoveEmptyValue.php
index 58096e3f3c6..272a0895e99 100644
--- a/apps/dav/lib/Migration/CalDAVRemoveEmptyValue.php
+++ b/apps/dav/lib/Migration/CalDAVRemoveEmptyValue.php
@@ -107,7 +107,7 @@ class CalDAVRemoveEmptyValue implements IRepairStep {
 			$query->select($query->func()->count('*', 'num_entries'))
 				->from('calendarobjects');
 			$result = $query->execute();
-			$count = $result->fetchColumn();
+			$count = $result->fetchOne();
 			$result->closeCursor();
 
 			$numChunks = ceil($count / $chunkSize);
diff --git a/apps/dav/lib/Migration/RegisterBuildReminderIndexBackgroundJob.php b/apps/dav/lib/Migration/RegisterBuildReminderIndexBackgroundJob.php
index 0f3ed1f0ad8..53087ff467f 100644
--- a/apps/dav/lib/Migration/RegisterBuildReminderIndexBackgroundJob.php
+++ b/apps/dav/lib/Migration/RegisterBuildReminderIndexBackgroundJob.php
@@ -88,7 +88,7 @@ class RegisterBuildReminderIndexBackgroundJob implements IRepairStep {
 		$query->select($query->createFunction('MAX(' . $query->getColumnName('id') . ')'))
 			->from('calendarobjects');
 		$result = $query->execute();
-		$maxId = (int) $result->fetchColumn();
+		$maxId = (int) $result->fetchOne();
 		$result->closeCursor();
 
 		$output->info('Add background job');
diff --git a/apps/files_sharing/lib/Command/CleanupRemoteStorages.php b/apps/files_sharing/lib/Command/CleanupRemoteStorages.php
index 259e55ff620..db18e7d2499 100644
--- a/apps/files_sharing/lib/Command/CleanupRemoteStorages.php
+++ b/apps/files_sharing/lib/Command/CleanupRemoteStorages.php
@@ -106,7 +106,7 @@ class CleanupRemoteStorages extends Command {
 				IQueryBuilder::PARAM_STR)
 			);
 		$result = $queryBuilder->execute();
-		$count = $result->fetchColumn();
+		$count = $result->fetchOne();
 		$output->writeln("$count files can be deleted for storage $numericId");
 	}
 
diff --git a/apps/files_sharing/lib/External/Manager.php b/apps/files_sharing/lib/External/Manager.php
index d02ac97ba39..534dd0d2c51 100644
--- a/apps/files_sharing/lib/External/Manager.php
+++ b/apps/files_sharing/lib/External/Manager.php
@@ -33,6 +33,7 @@
 
 namespace OCA\Files_Sharing\External;
 
+use Doctrine\DBAL\Driver\Exception;
 use OC\Files\Filesystem;
 use OCA\FederatedFileSharing\Events\FederatedShareAddedEvent;
 use OCA\Files_Sharing\Helper;
@@ -129,7 +130,7 @@ class Manager {
 	 * @param string $remoteId
 	 * @param int $parent
 	 * @return Mount|null
-	 * @throws \Doctrine\DBAL\DBALException
+	 * @throws \Doctrine\DBAL\Exception
 	 */
 	public function addShare($remote, $token, $password, $name, $owner, $shareType, $accepted = false, $user = null, $remoteId = '', $parent = -1) {
 		$user = $user ? $user : $this->uid;
@@ -199,15 +200,17 @@ class Manager {
 	 * @param $remoteId
 	 * @param $parent
 	 * @param $shareType
-	 * @return bool
+	 *
+	 * @return void
+	 * @throws \Doctrine\DBAL\Driver\Exception
 	 */
-	private function writeShareToDb($remote, $token, $password, $name, $owner, $user, $mountPoint, $hash, $accepted, $remoteId, $parent, $shareType) {
+	private function writeShareToDb($remote, $token, $password, $name, $owner, $user, $mountPoint, $hash, $accepted, $remoteId, $parent, $shareType): void {
 		$query = $this->connection->prepare('
 				INSERT INTO `*PREFIX*share_external`
 					(`remote`, `share_token`, `password`, `name`, `owner`, `user`, `mountpoint`, `mountpoint_hash`, `accepted`, `remote_id`, `parent`, `share_type`)
 				VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
 			');
-		return $query->execute([$remote, $token, $password, $name, $owner, $user, $mountPoint, $hash, $accepted, $remoteId, $parent, $shareType]);
+		$query->execute([$remote, $token, $password, $name, $owner, $user, $mountPoint, $hash, $accepted, $remoteId, $parent, $shareType]);
 	}
 
 	/**
@@ -222,9 +225,8 @@ class Manager {
 			FROM  `*PREFIX*share_external`
 			WHERE `id` = ?');
 		$result = $getShare->execute([$id]);
-
-		$share = $result ? $getShare->fetch() : [];
-
+		$share = $result->fetch();
+		$result->closeCursor();
 		$validShare = is_array($share) && isset($share['share_type']) && isset($share['user']);
 
 		// check if the user is allowed to access it
@@ -267,19 +269,24 @@ class Manager {
 				WHERE `id` = ? AND `user` = ?');
 				$userShareAccepted = $acceptShare->execute([1, $mountPoint, $hash, $id, $this->uid]);
 			} else {
-				$result = $this->writeShareToDb(
-					$share['remote'],
-					$share['share_token'],
-					$share['password'],
-					$share['name'],
-					$share['owner'],
-					$this->uid,
-					$mountPoint, $hash, 1,
-					$share['remote_id'],
-					$id,
-					$share['share_type']);
+				try {
+					$this->writeShareToDb(
+						$share['remote'],
+						$share['share_token'],
+						$share['password'],
+						$share['name'],
+						$share['owner'],
+						$this->uid,
+						$mountPoint, $hash, 1,
+						$share['remote_id'],
+						$id,
+						$share['share_type']);
+					$result = true;
+				} catch (Exception $e) {
+					$result = false;
+				}
 			}
-			if ($userShareAccepted === true) {
+			if ($userShareAccepted !== false) {
 				$this->sendFeedbackToRemote($share['remote'], $share['share_token'], $share['remote_id'], 'accept');
 				$event = new FederatedShareAddedEvent($share['remote']);
 				$this->eventDispatcher->dispatchTyped($event);
@@ -312,19 +319,24 @@ class Manager {
 			$this->processNotification($id);
 			$result = true;
 		} elseif ($share && (int)$share['share_type'] === IShare::TYPE_GROUP) {
-			$result = $this->writeShareToDb(
-				$share['remote'],
-				$share['share_token'],
-				$share['password'],
-				$share['name'],
-				$share['owner'],
-				$this->uid,
-				$share['mountpoint'],
-				$share['mountpoint_hash'],
-				0,
-				$share['remote_id'],
-				$id,
-				$share['share_type']);
+			try {
+				$this->writeShareToDb(
+					$share['remote'],
+					$share['share_token'],
+					$share['password'],
+					$share['name'],
+					$share['owner'],
+					$this->uid,
+					$share['mountpoint'],
+					$share['mountpoint_hash'],
+					0,
+					$share['remote_id'],
+					$id,
+					$share['share_type']);
+				$result = true;
+			} catch (Exception $e) {
+				$result = false;
+			}
 			$this->processNotification($id);
 		}
 
@@ -484,47 +496,50 @@ class Manager {
 		return $result;
 	}
 
-	public function removeShare($mountPoint) {
+	public function removeShare($mountPoint): bool {
 		$mountPointObj = $this->mountManager->find($mountPoint);
 		$id = $mountPointObj->getStorage()->getCache()->getId('');
 
 		$mountPoint = $this->stripPath($mountPoint);
 		$hash = md5($mountPoint);
 
-		$getShare = $this->connection->prepare('
-			SELECT `remote`, `share_token`, `remote_id`, `share_type`, `id`
-			FROM  `*PREFIX*share_external`
-			WHERE `mountpoint_hash` = ? AND `user` = ?');
-		$result = $getShare->execute([$hash, $this->uid]);
-
-		$share = $getShare->fetch();
-		$getShare->closeCursor();
-		if ($result && $share !== false && (int)$share['share_type'] === IShare::TYPE_USER) {
-			try {
-				$this->sendFeedbackToRemote($share['remote'], $share['share_token'], $share['remote_id'], 'decline');
-			} catch (\Throwable $e) {
-				// if we fail to notify the remote (probably cause the remote is down)
-				// we still want the share to be gone to prevent undeletable remotes
+		try {
+			$getShare = $this->connection->prepare('
+				SELECT `remote`, `share_token`, `remote_id`, `share_type`, `id`
+				FROM  `*PREFIX*share_external`
+				WHERE `mountpoint_hash` = ? AND `user` = ?');
+			$result = $getShare->execute([$hash, $this->uid]);
+			$share = $result->fetch();
+			$result->closeCursor();
+			if ($share !== false && (int)$share['share_type'] === IShare::TYPE_USER) {
+				try {
+					$this->sendFeedbackToRemote($share['remote'], $share['share_token'], $share['remote_id'], 'decline');
+				} catch (\Throwable $e) {
+					// if we fail to notify the remote (probably cause the remote is down)
+					// we still want the share to be gone to prevent undeletable remotes
+				}
+
+				$query = $this->connection->prepare('
+				DELETE FROM `*PREFIX*share_external`
+				WHERE `id` = ?
+				');
+				$deleteResult = $query->execute([(int)$share['id']]);
+				$deleteResult->closeCursor();
+			} elseif ($share !== false && (int)$share['share_type'] === IShare::TYPE_GROUP) {
+				$query = $this->connection->prepare('
+					UPDATE `*PREFIX*share_external`
+					SET `accepted` = ?
+					WHERE `id` = ?');
+				$updateResult = $query->execute([0, (int)$share['id']]);
+				$updateResult->closeCursor();
 			}
 
-			$query = $this->connection->prepare('
-			DELETE FROM `*PREFIX*share_external`
-			WHERE `id` = ?
-			');
-			$result = (bool)$query->execute([(int)$share['id']]);
-		} elseif ($result && $share !== false && (int)$share['share_type'] === IShare::TYPE_GROUP) {
-			$query = $this->connection->prepare('
-				UPDATE `*PREFIX*share_external`
-				SET `accepted` = ?
-				WHERE `id` = ?');
-			$result = (bool)$query->execute([0, (int)$share['id']]);
-		}
-
-		if ($result) {
 			$this->removeReShares($id);
+		} catch (\Doctrine\DBAL\Exception $ex) {
+			return false;
 		}
 
-		return $result;
+		return true;
 	}
 
 	/**
@@ -554,27 +569,31 @@ class Manager {
 	 * remove all shares for user $uid if the user was deleted
 	 *
 	 * @param string $uid
-	 * @return bool
 	 */
-	public function removeUserShares($uid) {
-		$getShare = $this->connection->prepare('
-			SELECT `remote`, `share_token`, `remote_id`
-			FROM  `*PREFIX*share_external`
-			WHERE `user` = ?');
-		$result = $getShare->execute([$uid]);
-
-		if ($result) {
-			$shares = $getShare->fetchAll();
+	public function removeUserShares($uid): bool {
+		try {
+			$getShare = $this->connection->prepare('
+				SELECT `remote`, `share_token`, `remote_id`
+				FROM  `*PREFIX*share_external`
+				WHERE `user` = ?');
+			$result = $getShare->execute([$uid]);
+			$shares = $result->fetchAll();
+			$result->closeCursor();
 			foreach ($shares as $share) {
 				$this->sendFeedbackToRemote($share['remote'], $share['share_token'], $share['remote_id'], 'decline');
 			}
+
+			$query = $this->connection->prepare('
+				DELETE FROM `*PREFIX*share_external`
+				WHERE `user` = ?
+			');
+			$deleteResult = $query->execute([$uid]);
+			$deleteResult->closeCursor();
+		} catch (\Doctrine\DBAL\Exception $ex) {
+			return false;
 		}
 
-		$query = $this->connection->prepare('
-			DELETE FROM `*PREFIX*share_external`
-			WHERE `user` = ?
-		');
-		return (bool)$query->execute([$uid]);
+		return true;
 	}
 
 	/**
@@ -621,9 +640,14 @@ class Manager {
 		}
 		$query .= ' ORDER BY `id` ASC';
 
-		$shares = $this->connection->prepare($query);
-		$result = $shares->execute($parameters);
-
-		return $result ? $shares->fetchAll() : [];
+		$sharesQuery = $this->connection->prepare($query);
+		try {
+			$result = $sharesQuery->execute($parameters);
+			$shares = $result->fetchAll();
+			$result->closeCursor();
+			return $shares;
+		} catch (\Doctrine\DBAL\Exception $e) {
+			return [];
+		}
 	}
 }
diff --git a/apps/files_trashbin/tests/Command/CleanUpTest.php b/apps/files_trashbin/tests/Command/CleanUpTest.php
index 329089bcafa..dad73aaadfc 100644
--- a/apps/files_trashbin/tests/Command/CleanUpTest.php
+++ b/apps/files_trashbin/tests/Command/CleanUpTest.php
@@ -30,6 +30,7 @@ namespace OCA\Files_Trashbin\Tests\Command;
 use OC\User\Manager;
 use OCA\Files_Trashbin\Command\CleanUp;
 use OCP\Files\IRootFolder;
+use OCP\IDBConnection;
 use Symfony\Component\Console\Exception\InvalidOptionException;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
@@ -53,7 +54,7 @@ class CleanUpTest extends TestCase {
 	/** @var \PHPUnit\Framework\MockObject\MockObject | IRootFolder */
 	protected $rootFolder;
 
-	/** @var \OC\DB\Connection */
+	/** @var IDBConnection */
 	protected $dbConnection;
 
 	/** @var  string */
diff --git a/apps/settings/lib/Controller/CheckSetupController.php b/apps/settings/lib/Controller/CheckSetupController.php
index 5b004d753e2..6acd970c40e 100644
--- a/apps/settings/lib/Controller/CheckSetupController.php
+++ b/apps/settings/lib/Controller/CheckSetupController.php
@@ -44,8 +44,9 @@ namespace OCA\Settings\Controller;
 
 use bantu\IniGetWrapper\IniGetWrapper;
 use DirectoryIterator;
-use Doctrine\DBAL\DBALException;
+use Doctrine\DBAL\Exception;
 use Doctrine\DBAL\Platforms\SqlitePlatform;
+use Doctrine\DBAL\TransactionIsolationLevel;
 use Doctrine\DBAL\Types\Types;
 use GuzzleHttp\Exception\ClientException;
 use OC;
@@ -94,7 +95,7 @@ class CheckSetupController extends Controller {
 	private $logger;
 	/** @var EventDispatcherInterface */
 	private $dispatcher;
-	/** @var IDBConnection|Connection */
+	/** @var Connection */
 	private $db;
 	/** @var ILockingProvider */
 	private $lockingProvider;
@@ -116,7 +117,7 @@ class CheckSetupController extends Controller {
 								Checker $checker,
 								ILogger $logger,
 								EventDispatcherInterface $dispatcher,
-								IDBConnection $db,
+								Connection $db,
 								ILockingProvider $lockingProvider,
 								IDateTimeFormatter $dateTimeFormatter,
 								MemoryInfo $memoryInfo,
@@ -492,8 +493,8 @@ Raw output
 				return true;
 			}
 
-			return $this->db->getTransactionIsolation() === Connection::TRANSACTION_READ_COMMITTED;
-		} catch (DBALException $e) {
+			return $this->db->getTransactionIsolation() === TransactionIsolationLevel::READ_COMMITTED;
+		} catch (Exception $e) {
 			// ignore
 		}
 
diff --git a/apps/user_ldap/lib/Mapping/AbstractMapping.php b/apps/user_ldap/lib/Mapping/AbstractMapping.php
index 15f95744cd0..f9f2b125d0e 100644
--- a/apps/user_ldap/lib/Mapping/AbstractMapping.php
+++ b/apps/user_ldap/lib/Mapping/AbstractMapping.php
@@ -27,7 +27,9 @@
 
 namespace OCA\User_LDAP\Mapping;
 
+use Doctrine\DBAL\Exception;
 use OC\DB\QueryBuilder\QueryBuilder;
+use OCP\DB\IPreparedStatement;
 
 /**
  * Class AbstractMapping
@@ -95,24 +97,32 @@ abstract class AbstractMapping {
 			WHERE `' . $compareCol . '` = ?
 		');
 
-		$res = $query->execute([$search]);
-		if ($res !== false) {
-			return $query->fetchColumn();
+		try {
+			$res = $query->execute([$search]);
+			$data = $res->fetchOne();
+			$res->closeCursor();
+			return $data;
+		} catch (Exception $e) {
+			return false;
 		}
-
-		return false;
 	}
 
 	/**
 	 * Performs a DELETE or UPDATE query to the database.
 	 *
-	 * @param \Doctrine\DBAL\Driver\Statement $query
+	 * @param IPreparedStatement $statement
 	 * @param array $parameters
 	 * @return bool true if at least one row was modified, false otherwise
 	 */
-	protected function modify($query, $parameters) {
-		$result = $query->execute($parameters);
-		return ($result === true && $query->rowCount() > 0);
+	protected function modify(IPreparedStatement $statement, $parameters) {
+		try {
+			$result = $statement->execute($parameters);
+			$updated = $result->rowCount() > 0;
+			$result->closeCursor();
+			return $updated;
+		} catch (Exception $e) {
+			return false;
+		}
 	}
 
 	/**
@@ -139,13 +149,13 @@ abstract class AbstractMapping {
 	 */
 	public function setDNbyUUID($fdn, $uuid) {
 		$oldDn = $this->getDnByUUID($uuid);
-		$query = $this->dbc->prepare('
+		$statement = $this->dbc->prepare('
 			UPDATE `' . $this->getTableName() . '`
 			SET `ldap_dn` = ?
 			WHERE `directory_uuid` = ?
 		');
 
-		$r = $this->modify($query, [$fdn, $uuid]);
+		$r = $this->modify($statement, [$fdn, $uuid]);
 
 		if ($r && is_string($oldDn) && isset($this->cache[$oldDn])) {
 			$this->cache[$fdn] = $this->cache[$oldDn];
@@ -165,7 +175,7 @@ abstract class AbstractMapping {
 	 * @return bool
 	 */
 	public function setUUIDbyDN($uuid, $fdn) {
-		$query = $this->dbc->prepare('
+		$statement = $this->dbc->prepare('
 			UPDATE `' . $this->getTableName() . '`
 			SET `directory_uuid` = ?
 			WHERE `ldap_dn` = ?
@@ -173,7 +183,7 @@ abstract class AbstractMapping {
 
 		unset($this->cache[$fdn]);
 
-		return $this->modify($query, [$uuid, $fdn]);
+		return $this->modify($statement, [$uuid, $fdn]);
 	}
 
 	/**
@@ -215,18 +225,20 @@ abstract class AbstractMapping {
 	 * @return string[]
 	 */
 	public function getNamesBySearch($search, $prefixMatch = "", $postfixMatch = "") {
-		$query = $this->dbc->prepare('
+		$statement = $this->dbc->prepare('
 			SELECT `owncloud_name`
 			FROM `' . $this->getTableName() . '`
 			WHERE `owncloud_name` LIKE ?
 		');
 
-		$res = $query->execute([$prefixMatch . $this->dbc->escapeLikeParameter($search) . $postfixMatch]);
+		try {
+			$res = $statement->execute([$prefixMatch . $this->dbc->escapeLikeParameter($search) . $postfixMatch]);
+		} catch (Exception $e) {
+			return [];
+		}
 		$names = [];
-		if ($res !== false) {
-			while ($row = $query->fetch()) {
-				$names[] = $row['owncloud_name'];
-			}
+		while ($row = $res->fetch()) {
+			$names[] = $row['owncloud_name'];
 		}
 		return $names;
 	}
@@ -323,15 +335,15 @@ abstract class AbstractMapping {
 	 * @return bool
 	 */
 	public function unmap($name) {
-		$query = $this->dbc->prepare('
+		$statement = $this->dbc->prepare('
 			DELETE FROM `' . $this->getTableName() . '`
 			WHERE `owncloud_name` = ?');
 
-		return $this->modify($query, [$name]);
+		return $this->modify($statement, [$name]);
 	}
 
 	/**
-	 * Truncate's the mapping table
+	 * Truncates the mapping table
 	 *
 	 * @return bool
 	 */
@@ -339,7 +351,13 @@ abstract class AbstractMapping {
 		$sql = $this->dbc
 			->getDatabasePlatform()
 			->getTruncateTableSQL('`' . $this->getTableName() . '`');
-		return $this->dbc->prepare($sql)->execute();
+		try {
+			$this->dbc->executeQuery($sql);
+
+			return true;
+		} catch (Exception $e) {
+			return false;
+		}
 	}
 
 	/**
@@ -357,7 +375,7 @@ abstract class AbstractMapping {
 			->from($this->getTableName());
 		$cursor = $picker->execute();
 		$result = true;
-		while ($id = $cursor->fetchColumn(0)) {
+		while ($id = $cursor->fetchOne()) {
 			$preCallback($id);
 			if ($isUnmapped = $this->unmap($id)) {
 				$postCallback($id);
@@ -378,7 +396,7 @@ abstract class AbstractMapping {
 		$query = $qb->select($qb->func()->count('ldap_dn'))
 			->from($this->getTableName());
 		$res = $query->execute();
-		$count = $res->fetchColumn();
+		$count = $res->fetchOne();
 		$res->closeCursor();
 		return (int)$count;
 	}
diff --git a/apps/workflowengine/lib/Controller/AWorkflowController.php b/apps/workflowengine/lib/Controller/AWorkflowController.php
index 6d109f7dccf..8b0d35ef62e 100644
--- a/apps/workflowengine/lib/Controller/AWorkflowController.php
+++ b/apps/workflowengine/lib/Controller/AWorkflowController.php
@@ -25,7 +25,7 @@ declare(strict_types=1);
 
 namespace OCA\WorkflowEngine\Controller;
 
-use Doctrine\DBAL\DBALException;
+use Doctrine\DBAL\Exception;
 use OCA\WorkflowEngine\Helper\ScopeContext;
 use OCA\WorkflowEngine\Manager;
 use OCP\AppFramework\Http\DataResponse;
@@ -112,7 +112,7 @@ abstract class AWorkflowController extends OCSController {
 			throw new OCSBadRequestException($e->getMessage(), $e);
 		} catch (\DomainException $e) {
 			throw new OCSForbiddenException($e->getMessage(), $e);
-		} catch (DBALException $e) {
+		} catch (Exception $e) {
 			throw new OCSException('An internal error occurred', $e->getCode(), $e);
 		}
 	}
@@ -139,7 +139,7 @@ abstract class AWorkflowController extends OCSController {
 			throw new OCSBadRequestException($e->getMessage(), $e);
 		} catch (\DomainException $e) {
 			throw new OCSForbiddenException($e->getMessage(), $e);
-		} catch (DBALException $e) {
+		} catch (Exception $e) {
 			throw new OCSException('An internal error occurred', $e->getCode(), $e);
 		}
 	}
@@ -157,7 +157,7 @@ abstract class AWorkflowController extends OCSController {
 			throw new OCSBadRequestException($e->getMessage(), $e);
 		} catch (\DomainException $e) {
 			throw new OCSForbiddenException($e->getMessage(), $e);
-		} catch (DBALException $e) {
+		} catch (Exception $e) {
 			throw new OCSException('An internal error occurred', $e->getCode(), $e);
 		}
 	}
diff --git a/apps/workflowengine/lib/Manager.php b/apps/workflowengine/lib/Manager.php
index 87c3c5de6b3..8c37e4d9885 100644
--- a/apps/workflowengine/lib/Manager.php
+++ b/apps/workflowengine/lib/Manager.php
@@ -21,7 +21,7 @@
 
 namespace OCA\WorkflowEngine;
 
-use Doctrine\DBAL\DBALException;
+use Doctrine\DBAL\Exception;
 use OC\Cache\CappedMemoryCache;
 use OCA\WorkflowEngine\AppInfo\Application;
 use OCA\WorkflowEngine\Check\FileMimeType;
@@ -290,7 +290,7 @@ class Manager implements IManager {
 	 * @param string $operation
 	 * @return array The added operation
 	 * @throws \UnexpectedValueException
-	 * @throws DBALException
+	 * @throw Exception
 	 */
 	public function addOperation(
 		string $class,
@@ -315,7 +315,7 @@ class Manager implements IManager {
 			$this->addScope($id, $scope);
 
 			$this->connection->commit();
-		} catch (DBALException $e) {
+		} catch (Exception $e) {
 			$this->connection->rollBack();
 			throw $e;
 		}
@@ -342,7 +342,7 @@ class Manager implements IManager {
 		$result = $qb->execute();
 
 		$this->operationsByScope[$scopeContext->getHash()] = [];
-		while ($opId = $result->fetchColumn(0)) {
+		while ($opId = $result->fetchOne()) {
 			$this->operationsByScope[$scopeContext->getHash()][] = (int)$opId;
 		}
 		$result->closeCursor();
@@ -358,7 +358,7 @@ class Manager implements IManager {
 	 * @return array The updated operation
 	 * @throws \UnexpectedValueException
 	 * @throws \DomainException
-	 * @throws DBALException
+	 * @throws Exception
 	 */
 	public function updateOperation(
 		int $id,
@@ -392,7 +392,7 @@ class Manager implements IManager {
 				->where($query->expr()->eq('id', $query->createNamedParameter($id)));
 			$query->execute();
 			$this->connection->commit();
-		} catch (DBALException $e) {
+		} catch (Exception $e) {
 			$this->connection->rollBack();
 			throw $e;
 		}
@@ -405,7 +405,7 @@ class Manager implements IManager {
 	 * @param int $id
 	 * @return bool
 	 * @throws \UnexpectedValueException
-	 * @throws DBALException
+	 * @throws Exception
 	 * @throws \DomainException
 	 */
 	public function deleteOperation($id, ScopeContext $scopeContext) {
@@ -425,7 +425,7 @@ class Manager implements IManager {
 					->execute();
 			}
 			$this->connection->commit();
-		} catch (DBALException $e) {
+		} catch (Exception $e) {
 			$this->connection->rollBack();
 			throw $e;
 		}
diff --git a/apps/workflowengine/lib/Migration/PopulateNewlyIntroducedDatabaseFields.php b/apps/workflowengine/lib/Migration/PopulateNewlyIntroducedDatabaseFields.php
index 50b38f81993..290dae4c67a 100644
--- a/apps/workflowengine/lib/Migration/PopulateNewlyIntroducedDatabaseFields.php
+++ b/apps/workflowengine/lib/Migration/PopulateNewlyIntroducedDatabaseFields.php
@@ -25,7 +25,7 @@ declare(strict_types=1);
 
 namespace OCA\WorkflowEngine\Migration;
 
-use Doctrine\DBAL\Driver\Statement;
+use OCP\DB\IResult;
 use OCP\IDBConnection;
 use OCP\Migration\IOutput;
 use OCP\Migration\IRepairStep;
@@ -52,17 +52,17 @@ class PopulateNewlyIntroducedDatabaseFields implements IRepairStep {
 		$result->closeCursor();
 	}
 
-	protected function populateScopeTable(Statement $ids): void {
+	protected function populateScopeTable(IResult $ids): void {
 		$qb = $this->dbc->getQueryBuilder();
 
 		$insertQuery = $qb->insert('flow_operations_scope');
-		while ($id = $ids->fetchColumn(0)) {
+		while ($id = $ids->fetchOne()) {
 			$insertQuery->values(['operation_id' => $qb->createNamedParameter($id), 'type' => IManager::SCOPE_ADMIN]);
 			$insertQuery->execute();
 		}
 	}
 
-	protected function getIdsWithoutScope(): Statement {
+	protected function getIdsWithoutScope(): IResult {
 		$qb = $this->dbc->getQueryBuilder();
 		$selectQuery = $qb->select('o.id')
 			->from('flow_operations', 'o')
@@ -71,6 +71,8 @@ class PopulateNewlyIntroducedDatabaseFields implements IRepairStep {
 		// The left join operation is not necessary, usually, but it's a safe-guard
 		// in case the repair step is executed multiple times for whatever reason.
 
-		return $selectQuery->execute();
+		/** @var IResult $result */
+		$result = $selectQuery->execute();
+		return $result;
 	}
 }
diff --git a/build/psalm-baseline.xml b/build/psalm-baseline.xml
index 762f58131b5..63c35a969b0 100644
--- a/build/psalm-baseline.xml
+++ b/build/psalm-baseline.xml
@@ -3061,10 +3061,14 @@
     </MoreSpecificImplementedParamType>
   </file>
   <file src="lib/private/Archive/TAR.php">
-    <InvalidReturnStatement occurrences="1">
+    <FalsableReturnStatement occurrences="1">
+      <code>false</code>
+    </FalsableReturnStatement>
+    <InvalidReturnStatement occurrences="2">
       <code>$this-&gt;tar-&gt;extractInString($path)</code>
     </InvalidReturnStatement>
-    <InvalidReturnType occurrences="1">
+    <InvalidReturnType occurrences="2">
+      <code>resource</code>
       <code>string</code>
     </InvalidReturnType>
     <UndefinedDocblockClass occurrences="1">
@@ -3076,6 +3080,10 @@
       <code>boolean|null</code>
       <code>boolean|null</code>
     </ImplementedReturnTypeMismatch>
+    <InvalidReturnStatement occurrences="1"/>
+    <InvalidReturnType occurrences="1">
+      <code>resource</code>
+    </InvalidReturnType>
   </file>
   <file src="lib/private/Authentication/LoginCredentials/Store.php">
     <RedundantCondition occurrences="1">
@@ -3584,6 +3592,9 @@
     <ImplementedParamTypeMismatch occurrences="1">
       <code>$eventName</code>
     </ImplementedParamTypeMismatch>
+    <ImplementedReturnTypeMismatch occurrences="1">
+      <code>void</code>
+    </ImplementedReturnTypeMismatch>
     <InvalidArgument occurrences="1">
       <code>$eventName</code>
     </InvalidArgument>
diff --git a/core/Application.php b/core/Application.php
index 987358b5b97..c3cb6f02ed5 100644
--- a/core/Application.php
+++ b/core/Application.php
@@ -41,6 +41,7 @@ use OC\Authentication\Listeners\UserDeletedStoreCleanupListener;
 use OC\Authentication\Listeners\UserDeletedTokenCleanupListener;
 use OC\Authentication\Notifications\Notifier as AuthenticationNotifier;
 use OC\Core\Notification\CoreNotifier;
+use OC\DB\Connection;
 use OC\DB\MissingColumnInformation;
 use OC\DB\MissingIndexInformation;
 use OC\DB\MissingPrimaryKeyInformation;
@@ -82,7 +83,7 @@ class Application extends App {
 				/** @var MissingIndexInformation $subject */
 				$subject = $event->getSubject();
 
-				$schema = new SchemaWrapper($container->query(IDBConnection::class));
+				$schema = new SchemaWrapper($container->query(Connection::class));
 
 				if ($schema->hasTable('share')) {
 					$table = $schema->getTable('share');
@@ -192,7 +193,7 @@ class Application extends App {
 				/** @var MissingPrimaryKeyInformation $subject */
 				$subject = $event->getSubject();
 
-				$schema = new SchemaWrapper($container->query(IDBConnection::class));
+				$schema = new SchemaWrapper($container->query(Connection::class));
 
 				if ($schema->hasTable('federated_reshares')) {
 					$table = $schema->getTable('federated_reshares');
@@ -249,7 +250,7 @@ class Application extends App {
 				/** @var MissingColumnInformation $subject */
 				$subject = $event->getSubject();
 
-				$schema = new SchemaWrapper($container->query(IDBConnection::class));
+				$schema = new SchemaWrapper($container->query(Connection::class));
 
 				if ($schema->hasTable('comments')) {
 					$table = $schema->getTable('comments');
diff --git a/core/Command/Db/AddMissingColumns.php b/core/Command/Db/AddMissingColumns.php
index 3ace75b4eef..4b7fa039956 100644
--- a/core/Command/Db/AddMissingColumns.php
+++ b/core/Command/Db/AddMissingColumns.php
@@ -26,6 +26,7 @@ declare(strict_types=1);
 
 namespace OC\Core\Command\Db;
 
+use OC\DB\Connection;
 use OC\DB\SchemaWrapper;
 use OCP\IDBConnection;
 use Symfony\Component\Console\Command\Command;
@@ -44,13 +45,13 @@ use Symfony\Component\EventDispatcher\GenericEvent;
  */
 class AddMissingColumns extends Command {
 
-	/** @var IDBConnection */
+	/** @var Connection */
 	private $connection;
 
 	/** @var EventDispatcherInterface */
 	private $dispatcher;
 
-	public function __construct(IDBConnection $connection, EventDispatcherInterface $dispatcher) {
+	public function __construct(Connection $connection, EventDispatcherInterface $dispatcher) {
 		parent::__construct();
 
 		$this->connection = $connection;
diff --git a/core/Command/Db/AddMissingIndices.php b/core/Command/Db/AddMissingIndices.php
index 5cbd6ee405d..1acff55fa40 100644
--- a/core/Command/Db/AddMissingIndices.php
+++ b/core/Command/Db/AddMissingIndices.php
@@ -33,6 +33,7 @@ declare(strict_types=1);
 
 namespace OC\Core\Command\Db;
 
+use OC\DB\Connection;
 use OC\DB\SchemaWrapper;
 use OCP\IDBConnection;
 use Symfony\Component\Console\Command\Command;
@@ -51,13 +52,13 @@ use Symfony\Component\EventDispatcher\GenericEvent;
  */
 class AddMissingIndices extends Command {
 
-	/** @var IDBConnection */
+	/** @var Connection */
 	private $connection;
 
 	/** @var EventDispatcherInterface */
 	private $dispatcher;
 
-	public function __construct(IDBConnection $connection, EventDispatcherInterface $dispatcher) {
+	public function __construct(Connection $connection, EventDispatcherInterface $dispatcher) {
 		parent::__construct();
 
 		$this->connection = $connection;
diff --git a/core/Command/Db/AddMissingPrimaryKeys.php b/core/Command/Db/AddMissingPrimaryKeys.php
index ef3d6a05f2e..7113ecb210f 100644
--- a/core/Command/Db/AddMissingPrimaryKeys.php
+++ b/core/Command/Db/AddMissingPrimaryKeys.php
@@ -26,6 +26,7 @@ declare(strict_types=1);
 
 namespace OC\Core\Command\Db;
 
+use OC\DB\Connection;
 use OC\DB\SchemaWrapper;
 use OCP\IDBConnection;
 use Symfony\Component\Console\Command\Command;
@@ -44,13 +45,13 @@ use Symfony\Component\EventDispatcher\GenericEvent;
  */
 class AddMissingPrimaryKeys extends Command {
 
-	/** @var IDBConnection */
+	/** @var Connection */
 	private $connection;
 
 	/** @var EventDispatcherInterface */
 	private $dispatcher;
 
-	public function __construct(IDBConnection $connection, EventDispatcherInterface $dispatcher) {
+	public function __construct(Connection $connection, EventDispatcherInterface $dispatcher) {
 		parent::__construct();
 
 		$this->connection = $connection;
diff --git a/core/Command/Db/ConvertFilecacheBigInt.php b/core/Command/Db/ConvertFilecacheBigInt.php
index 77f5034315c..6001de6fb9e 100644
--- a/core/Command/Db/ConvertFilecacheBigInt.php
+++ b/core/Command/Db/ConvertFilecacheBigInt.php
@@ -34,8 +34,8 @@ namespace OC\Core\Command\Db;
 use Doctrine\DBAL\Platforms\SqlitePlatform;
 use Doctrine\DBAL\Types\Type;
 use Doctrine\DBAL\Types\Types;
+use OC\DB\Connection;
 use OC\DB\SchemaWrapper;
-use OCP\IDBConnection;
 use Symfony\Component\Console\Command\Command;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
@@ -43,13 +43,13 @@ use Symfony\Component\Console\Question\ConfirmationQuestion;
 
 class ConvertFilecacheBigInt extends Command {
 
-	/** @var IDBConnection */
+	/** @var Connection */
 	private $connection;
 
 	/**
-	 * @param IDBConnection $connection
+	 * @param Connection $connection
 	 */
-	public function __construct(IDBConnection $connection) {
+	public function __construct(Connection $connection) {
 		$this->connection = $connection;
 		parent::__construct();
 	}
diff --git a/core/Command/Db/ConvertMysqlToMB4.php b/core/Command/Db/ConvertMysqlToMB4.php
index 4305f446286..55633ea9941 100644
--- a/core/Command/Db/ConvertMysqlToMB4.php
+++ b/core/Command/Db/ConvertMysqlToMB4.php
@@ -24,7 +24,7 @@
 
 namespace OC\Core\Command\Db;
 
-use Doctrine\DBAL\Platforms\MySqlPlatform;
+use Doctrine\DBAL\Platforms\MySQLPlatform;
 use OC\DB\MySqlTools;
 use OC\Migration\ConsoleOutput;
 use OC\Repair\Collation;
@@ -70,7 +70,7 @@ class ConvertMysqlToMB4 extends Command {
 	}
 
 	protected function execute(InputInterface $input, OutputInterface $output): int {
-		if (!$this->connection->getDatabasePlatform() instanceof MySqlPlatform) {
+		if (!$this->connection->getDatabasePlatform() instanceof MySQLPlatform) {
 			$output->writeln("This command is only valid for MySQL/MariaDB databases.");
 			return 1;
 		}
diff --git a/core/Command/Db/ConvertType.php b/core/Command/Db/ConvertType.php
index d89d57ff601..32b7492d967 100644
--- a/core/Command/Db/ConvertType.php
+++ b/core/Command/Db/ConvertType.php
@@ -33,9 +33,10 @@
 
 namespace OC\Core\Command\Db;
 
-use Doctrine\DBAL\DBALException;
+use Doctrine\DBAL\Exception;
+use Doctrine\DBAL\Schema\AbstractAsset;
 use Doctrine\DBAL\Schema\Table;
-use Doctrine\DBAL\Types\Type;
+use Doctrine\DBAL\Types\Types;
 use OC\DB\Connection;
 use OC\DB\ConnectionFactory;
 use OC\DB\MigrationService;
@@ -52,6 +53,8 @@ use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Console\Question\ConfirmationQuestion;
 use Symfony\Component\Console\Question\Question;
+use function preg_match;
+use function preg_quote;
 
 class ConvertType extends Command implements CompletionAwareInterface {
 	/**
@@ -192,7 +195,8 @@ class ConvertType extends Command implements CompletionAwareInterface {
 		$this->validateInput($input, $output);
 		$this->readPassword($input, $output);
 
-		$fromDB = \OC::$server->getDatabaseConnection();
+		/** @var Connection $fromDB */
+		$fromDB = \OC::$server->get(Connection::class);
 		$toDB = $this->getToDBConnection($input, $output);
 
 		if ($input->getOption('clear-schema')) {
@@ -283,9 +287,14 @@ class ConvertType extends Command implements CompletionAwareInterface {
 	}
 
 	protected function getTables(Connection $db) {
-		$filterExpression = '/^' . preg_quote($this->config->getSystemValue('dbtableprefix', 'oc_')) . '/';
-		$db->getConfiguration()->
-			setFilterSchemaAssetsExpression($filterExpression);
+		$db->getConfiguration()->setSchemaAssetsFilter(function ($asset) {
+			/** @var string|AbstractAsset $asset */
+			$filterExpression = '/^' . preg_quote($this->config->getSystemValue('dbtableprefix', 'oc_')) . '/';
+			if ($asset instanceof AbstractAsset) {
+				return preg_match($filterExpression, $asset->getName()) !== false;
+			}
+			return preg_match($filterExpression, $asset) !== false;
+		});
 		return $db->getSchemaManager()->listTableNames();
 	}
 
@@ -309,7 +318,7 @@ class ConvertType extends Command implements CompletionAwareInterface {
 		$query->select($query->func()->count('*', 'num_entries'))
 			->from($table->getName());
 		$result = $query->execute();
-		$count = $result->fetchColumn();
+		$count = $result->fetchOne();
 		$result->closeCursor();
 
 		$numChunks = ceil($count / $chunkSize);
@@ -330,7 +339,7 @@ class ConvertType extends Command implements CompletionAwareInterface {
 
 		try {
 			$orderColumns = $table->getPrimaryKeyColumns();
-		} catch (DBALException $e) {
+		} catch (Exception $e) {
 			$orderColumns = [];
 			foreach ($table->getColumns() as $column) {
 				$orderColumns[] = $column->getName();
@@ -384,11 +393,11 @@ class ConvertType extends Command implements CompletionAwareInterface {
 		$type = $table->getColumn($columnName)->getType()->getName();
 
 		switch ($type) {
-			case Type::BLOB:
-			case Type::TEXT:
+			case Types::BLOB:
+			case Types::TEXT:
 				$this->columnTypes[$tableName][$columnName] = IQueryBuilder::PARAM_LOB;
 				break;
-			case Type::BOOLEAN:
+			case Types::BOOLEAN:
 				$this->columnTypes[$tableName][$columnName] = IQueryBuilder::PARAM_BOOL;
 				break;
 			default:
diff --git a/core/Command/Db/Migrations/ExecuteCommand.php b/core/Command/Db/Migrations/ExecuteCommand.php
index 95f1acd14fe..cc3f7d67fc0 100644
--- a/core/Command/Db/Migrations/ExecuteCommand.php
+++ b/core/Command/Db/Migrations/ExecuteCommand.php
@@ -23,11 +23,10 @@
 
 namespace OC\Core\Command\Db\Migrations;
 
+use OC\DB\Connection;
 use OC\DB\MigrationService;
 use OC\Migration\ConsoleOutput;
-use OCP\App\IAppManager;
 use OCP\IConfig;
-use OCP\IDBConnection;
 use Stecman\Component\Symfony\Console\BashCompletion\Completion\CompletionAwareInterface;
 use Stecman\Component\Symfony\Console\BashCompletion\CompletionContext;
 use Symfony\Component\Console\Command\Command;
@@ -37,23 +36,19 @@ use Symfony\Component\Console\Output\OutputInterface;
 
 class ExecuteCommand extends Command implements CompletionAwareInterface {
 
-	/** @var IDBConnection */
+	/** @var Connection */
 	private $connection;
 
 	/** @var IConfig */
 	private $config;
 
-	/** @var IAppManager */
-	protected $appManager;
-
 	/**
 	 * ExecuteCommand constructor.
 	 *
-	 * @param IDBConnection $connection
+	 * @param Connection $connection
 	 * @param IConfig $config
-	 * @param IAppManager $appManager
 	 */
-	public function __construct(IDBConnection $connection, IAppManager $appManager, IConfig $config) {
+	public function __construct(Connection $connection, IConfig $config) {
 		$this->connection = $connection;
 		$this->config = $config;
 
diff --git a/core/Command/Db/Migrations/GenerateCommand.php b/core/Command/Db/Migrations/GenerateCommand.php
index fcafa9431c3..48fc59e77fb 100644
--- a/core/Command/Db/Migrations/GenerateCommand.php
+++ b/core/Command/Db/Migrations/GenerateCommand.php
@@ -25,10 +25,10 @@
 
 namespace OC\Core\Command\Db\Migrations;
 
+use OC\DB\Connection;
 use OC\DB\MigrationService;
 use OC\Migration\ConsoleOutput;
 use OCP\App\IAppManager;
-use OCP\IDBConnection;
 use Stecman\Component\Symfony\Console\BashCompletion\Completion\CompletionAwareInterface;
 use Stecman\Component\Symfony\Console\BashCompletion\CompletionContext;
 use Symfony\Component\Console\Command\Command;
@@ -83,17 +83,17 @@ class {{classname}} extends SimpleMigrationStep {
 }
 ';
 
-	/** @var IDBConnection */
+	/** @var Connection */
 	protected $connection;
 
 	/** @var IAppManager */
 	protected $appManager;
 
 	/**
-	 * @param IDBConnection $connection
+	 * @param Connection $connection
 	 * @param IAppManager $appManager
 	 */
-	public function __construct(IDBConnection $connection, IAppManager $appManager) {
+	public function __construct(Connection $connection, IAppManager $appManager) {
 		$this->connection = $connection;
 		$this->appManager = $appManager;
 
diff --git a/core/Command/Db/Migrations/GenerateFromSchemaFileCommand.php b/core/Command/Db/Migrations/GenerateFromSchemaFileCommand.php
index 71349c0fa51..9101957a97c 100644
--- a/core/Command/Db/Migrations/GenerateFromSchemaFileCommand.php
+++ b/core/Command/Db/Migrations/GenerateFromSchemaFileCommand.php
@@ -26,12 +26,12 @@
 namespace OC\Core\Command\Db\Migrations;
 
 use Doctrine\DBAL\Schema\Schema;
+use OC\DB\Connection;
 use OC\DB\MDB2SchemaReader;
 use OC\DB\MigrationService;
 use OC\Migration\ConsoleOutput;
 use OCP\App\IAppManager;
 use OCP\IConfig;
-use OCP\IDBConnection;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 
@@ -40,7 +40,7 @@ class GenerateFromSchemaFileCommand extends GenerateCommand {
 	/** @var IConfig */
 	protected $config;
 
-	public function __construct(IConfig $config, IAppManager $appManager, IDBConnection $connection) {
+	public function __construct(IConfig $config, IAppManager $appManager, Connection $connection) {
 		parent::__construct($connection, $appManager);
 		$this->config = $config;
 	}
diff --git a/core/Command/Db/Migrations/MigrateCommand.php b/core/Command/Db/Migrations/MigrateCommand.php
index 229288c794a..218c8aaf518 100644
--- a/core/Command/Db/Migrations/MigrateCommand.php
+++ b/core/Command/Db/Migrations/MigrateCommand.php
@@ -22,9 +22,9 @@
 
 namespace OC\Core\Command\Db\Migrations;
 
+use OC\DB\Connection;
 use OC\DB\MigrationService;
 use OC\Migration\ConsoleOutput;
-use OCP\IDBConnection;
 use Stecman\Component\Symfony\Console\BashCompletion\Completion\CompletionAwareInterface;
 use Stecman\Component\Symfony\Console\BashCompletion\CompletionContext;
 use Symfony\Component\Console\Command\Command;
@@ -34,13 +34,13 @@ use Symfony\Component\Console\Output\OutputInterface;
 
 class MigrateCommand extends Command implements CompletionAwareInterface {
 
-	/** @var IDBConnection */
+	/** @var Connection */
 	private $connection;
 
 	/**
-	 * @param IDBConnection $connection
+	 * @param Connection $connection
 	 */
-	public function __construct(IDBConnection $connection) {
+	public function __construct(Connection $connection) {
 		$this->connection = $connection;
 		parent::__construct();
 	}
diff --git a/core/Command/Db/Migrations/StatusCommand.php b/core/Command/Db/Migrations/StatusCommand.php
index 83763ee79b3..6c78bcd180c 100644
--- a/core/Command/Db/Migrations/StatusCommand.php
+++ b/core/Command/Db/Migrations/StatusCommand.php
@@ -24,9 +24,9 @@
 
 namespace OC\Core\Command\Db\Migrations;
 
+use OC\DB\Connection;
 use OC\DB\MigrationService;
 use OC\Migration\ConsoleOutput;
-use OCP\IDBConnection;
 use Stecman\Component\Symfony\Console\BashCompletion\Completion\CompletionAwareInterface;
 use Stecman\Component\Symfony\Console\BashCompletion\CompletionContext;
 use Symfony\Component\Console\Command\Command;
@@ -36,13 +36,10 @@ use Symfony\Component\Console\Output\OutputInterface;
 
 class StatusCommand extends Command implements CompletionAwareInterface {
 
-	/** @var IDBConnection */
+	/** @var Connection */
 	private $connection;
 
-	/**
-	 * @param IDBConnection $connection
-	 */
-	public function __construct(IDBConnection $connection) {
+	public function __construct(Connection $connection) {
 		$this->connection = $connection;
 		parent::__construct();
 	}
diff --git a/core/Migrations/Version16000Date20190427105638.php b/core/Migrations/Version16000Date20190427105638.php
index cf48108d9e9..a2a58c74495 100644
--- a/core/Migrations/Version16000Date20190427105638.php
+++ b/core/Migrations/Version16000Date20190427105638.php
@@ -60,7 +60,6 @@ class Version16000Date20190427105638 extends SimpleMigrationStep {
 	 * @param array $options
 	 * @return null|ISchemaWrapper
 	 * @throws \Doctrine\DBAL\Schema\SchemaException
-	 * @throws \Doctrine\DBAL\DBALException
 	 */
 	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options) {
 		/** @var ISchemaWrapper $schema */
diff --git a/core/Migrations/Version20000Date20201109081918.php b/core/Migrations/Version20000Date20201109081918.php
index 71c433a2138..c5a19d0cbfb 100644
--- a/core/Migrations/Version20000Date20201109081918.php
+++ b/core/Migrations/Version20000Date20201109081918.php
@@ -28,7 +28,7 @@ declare(strict_types=1);
 namespace OC\Core\Migrations;
 
 use Closure;
-use Doctrine\DBAL\Types\Type;
+use Doctrine\DBAL\Types\Types;
 use OCP\DB\ISchemaWrapper;
 use OCP\IDBConnection;
 use OCP\Migration\IOutput;
@@ -55,20 +55,20 @@ class Version20000Date20201109081918 extends SimpleMigrationStep {
 
 		if (!$schema->hasTable('storages_credentials')) {
 			$table = $schema->createTable('storages_credentials');
-			$table->addColumn('id', Type::BIGINT, [
+			$table->addColumn('id', Types::BIGINT, [
 				'autoincrement' => true,
 				'notnull' => true,
 				'length' => 64,
 			]);
-			$table->addColumn('user', Type::STRING, [
+			$table->addColumn('user', Types::STRING, [
 				'notnull' => false,
 				'length' => 64,
 			]);
-			$table->addColumn('identifier', Type::STRING, [
+			$table->addColumn('identifier', Types::STRING, [
 				'notnull' => true,
 				'length' => 64,
 			]);
-			$table->addColumn('credentials', Type::TEXT, [
+			$table->addColumn('credentials', Types::TEXT, [
 				'notnull' => false,
 			]);
 			$table->setPrimaryKey(['id']);
diff --git a/core/js/setupchecks.js b/core/js/setupchecks.js
index 9d3f1ddc508..c483454cb91 100644
--- a/core/js/setupchecks.js
+++ b/core/js/setupchecks.js
@@ -513,6 +513,7 @@
 					OC.SetupChecks.addGenericSetupCheck(data, 'OCA\\Settings\\SetupChecks\\PhpOutputBuffering', messages)
 					OC.SetupChecks.addGenericSetupCheck(data, 'OCA\\Settings\\SetupChecks\\LegacySSEKeyFormat', messages)
 					OC.SetupChecks.addGenericSetupCheck(data, 'OCA\\Settings\\SetupChecks\\CheckUserCertificates', messages)
+					OC.SetupChecks.addGenericSetupCheck(data, 'OCA\\Settings\\SetupChecks\\SupportedDatabase', messages)
 
 				} else {
 					messages.push({
diff --git a/core/register_command.php b/core/register_command.php
index fe998020d20..605c545554a 100644
--- a/core/register_command.php
+++ b/core/register_command.php
@@ -100,15 +100,15 @@ if (\OC::$server->getConfig()->getSystemValue('installed', false)) {
 
 	$application->add(new OC\Core\Command\Db\ConvertType(\OC::$server->getConfig(), new \OC\DB\ConnectionFactory(\OC::$server->getSystemConfig())));
 	$application->add(new OC\Core\Command\Db\ConvertMysqlToMB4(\OC::$server->getConfig(), \OC::$server->getDatabaseConnection(), \OC::$server->getURLGenerator(), \OC::$server->getLogger()));
-	$application->add(new OC\Core\Command\Db\ConvertFilecacheBigInt(\OC::$server->getDatabaseConnection()));
-	$application->add(new OC\Core\Command\Db\AddMissingIndices(\OC::$server->getDatabaseConnection(), \OC::$server->getEventDispatcher()));
-	$application->add(new OC\Core\Command\Db\AddMissingColumns(\OC::$server->getDatabaseConnection(), \OC::$server->getEventDispatcher()));
-	$application->add(new OC\Core\Command\Db\AddMissingPrimaryKeys(\OC::$server->getDatabaseConnection(), \OC::$server->getEventDispatcher()));
-	$application->add(new OC\Core\Command\Db\Migrations\StatusCommand(\OC::$server->getDatabaseConnection()));
-	$application->add(new OC\Core\Command\Db\Migrations\MigrateCommand(\OC::$server->getDatabaseConnection()));
-	$application->add(new OC\Core\Command\Db\Migrations\GenerateCommand(\OC::$server->getDatabaseConnection(), \OC::$server->getAppManager()));
-	$application->add(new OC\Core\Command\Db\Migrations\GenerateFromSchemaFileCommand(\OC::$server->getConfig(), \OC::$server->getAppManager(), \OC::$server->getDatabaseConnection()));
-	$application->add(new OC\Core\Command\Db\Migrations\ExecuteCommand(\OC::$server->getDatabaseConnection(), \OC::$server->getAppManager(), \OC::$server->getConfig()));
+	$application->add(new OC\Core\Command\Db\ConvertFilecacheBigInt(\OC::$server->get(\OC\DB\Connection::class)));
+	$application->add(new OC\Core\Command\Db\AddMissingIndices(\OC::$server->get(\OC\DB\Connection::class), \OC::$server->getEventDispatcher()));
+	$application->add(new OC\Core\Command\Db\AddMissingColumns(\OC::$server->get(\OC\DB\Connection::class), \OC::$server->getEventDispatcher()));
+	$application->add(new OC\Core\Command\Db\AddMissingPrimaryKeys(\OC::$server->get(\OC\DB\Connection::class), \OC::$server->getEventDispatcher()));
+	$application->add(new OC\Core\Command\Db\Migrations\StatusCommand(\OC::$server->get(\OC\DB\Connection::class)));
+	$application->add(new OC\Core\Command\Db\Migrations\MigrateCommand(\OC::$server->get(\OC\DB\Connection::class)));
+	$application->add(new OC\Core\Command\Db\Migrations\GenerateCommand(\OC::$server->get(\OC\DB\Connection::class), \OC::$server->getAppManager()));
+	$application->add(new OC\Core\Command\Db\Migrations\GenerateFromSchemaFileCommand(\OC::$server->getConfig(), \OC::$server->getAppManager(), \OC::$server->get(\OC\DB\Connection::class)));
+	$application->add(new OC\Core\Command\Db\Migrations\ExecuteCommand(\OC::$server->get(\OC\DB\Connection::class), \OC::$server->getConfig()));
 
 	$application->add(new OC\Core\Command\Encryption\Disable(\OC::$server->getConfig()));
 	$application->add(new OC\Core\Command\Encryption\Enable(\OC::$server->getConfig(), \OC::$server->getEncryptionManager()));
diff --git a/lib/composer/composer/autoload_classmap.php b/lib/composer/composer/autoload_classmap.php
index 3a65a05c5a9..a69437f1d47 100644
--- a/lib/composer/composer/autoload_classmap.php
+++ b/lib/composer/composer/autoload_classmap.php
@@ -161,6 +161,8 @@ return array(
     'OCP\\Contacts\\ContactsMenu\\IProvider' => $baseDir . '/lib/public/Contacts/ContactsMenu/IProvider.php',
     'OCP\\Contacts\\Events\\ContactInteractedWithEvent' => $baseDir . '/lib/public/Contacts/Events/ContactInteractedWithEvent.php',
     'OCP\\Contacts\\IManager' => $baseDir . '/lib/public/Contacts/IManager.php',
+    'OCP\\DB\\IPreparedStatement' => $baseDir . '/lib/public/DB/IPreparedStatement.php',
+    'OCP\\DB\\IResult' => $baseDir . '/lib/public/DB/IResult.php',
     'OCP\\DB\\ISchemaWrapper' => $baseDir . '/lib/public/DB/ISchemaWrapper.php',
     'OCP\\DB\\QueryBuilder\\ICompositeExpression' => $baseDir . '/lib/public/DB/QueryBuilder/ICompositeExpression.php',
     'OCP\\DB\\QueryBuilder\\IExpressionBuilder' => $baseDir . '/lib/public/DB/QueryBuilder/IExpressionBuilder.php',
@@ -948,10 +950,10 @@ return array(
     'OC\\DB\\AdapterPgSql' => $baseDir . '/lib/private/DB/AdapterPgSql.php',
     'OC\\DB\\AdapterSqlite' => $baseDir . '/lib/private/DB/AdapterSqlite.php',
     'OC\\DB\\Connection' => $baseDir . '/lib/private/DB/Connection.php',
+    'OC\\DB\\ConnectionAdapter' => $baseDir . '/lib/private/DB/ConnectionAdapter.php',
     'OC\\DB\\ConnectionFactory' => $baseDir . '/lib/private/DB/ConnectionFactory.php',
     'OC\\DB\\MDB2SchemaManager' => $baseDir . '/lib/private/DB/MDB2SchemaManager.php',
     'OC\\DB\\MDB2SchemaReader' => $baseDir . '/lib/private/DB/MDB2SchemaReader.php',
-    'OC\\DB\\MDB2SchemaWriter' => $baseDir . '/lib/private/DB/MDB2SchemaWriter.php',
     'OC\\DB\\MigrationException' => $baseDir . '/lib/private/DB/MigrationException.php',
     'OC\\DB\\MigrationService' => $baseDir . '/lib/private/DB/MigrationService.php',
     'OC\\DB\\Migrator' => $baseDir . '/lib/private/DB/Migrator.php',
@@ -965,6 +967,7 @@ return array(
     'OC\\DB\\OracleMigrator' => $baseDir . '/lib/private/DB/OracleMigrator.php',
     'OC\\DB\\PgSqlTools' => $baseDir . '/lib/private/DB/PgSqlTools.php',
     'OC\\DB\\PostgreSqlMigrator' => $baseDir . '/lib/private/DB/PostgreSqlMigrator.php',
+    'OC\\DB\\PreparedStatement' => $baseDir . '/lib/private/DB/PreparedStatement.php',
     'OC\\DB\\QueryBuilder\\CompositeExpression' => $baseDir . '/lib/private/DB/QueryBuilder/CompositeExpression.php',
     'OC\\DB\\QueryBuilder\\ExpressionBuilder\\ExpressionBuilder' => $baseDir . '/lib/private/DB/QueryBuilder/ExpressionBuilder/ExpressionBuilder.php',
     'OC\\DB\\QueryBuilder\\ExpressionBuilder\\MySqlExpressionBuilder' => $baseDir . '/lib/private/DB/QueryBuilder/ExpressionBuilder/MySqlExpressionBuilder.php',
@@ -981,6 +984,7 @@ return array(
     'OC\\DB\\QueryBuilder\\QueryFunction' => $baseDir . '/lib/private/DB/QueryBuilder/QueryFunction.php',
     'OC\\DB\\QueryBuilder\\QuoteHelper' => $baseDir . '/lib/private/DB/QueryBuilder/QuoteHelper.php',
     'OC\\DB\\ReconnectWrapper' => $baseDir . '/lib/private/DB/ReconnectWrapper.php',
+    'OC\\DB\\ResultAdapter' => $baseDir . '/lib/private/DB/ResultAdapter.php',
     'OC\\DB\\SQLiteMigrator' => $baseDir . '/lib/private/DB/SQLiteMigrator.php',
     'OC\\DB\\SQLiteSessionInit' => $baseDir . '/lib/private/DB/SQLiteSessionInit.php',
     'OC\\DB\\SchemaWrapper' => $baseDir . '/lib/private/DB/SchemaWrapper.php',
diff --git a/lib/composer/composer/autoload_static.php b/lib/composer/composer/autoload_static.php
index 521991cff73..4c46c7bc43e 100644
--- a/lib/composer/composer/autoload_static.php
+++ b/lib/composer/composer/autoload_static.php
@@ -190,6 +190,8 @@ class ComposerStaticInit53792487c5a8370acc0b06b1a864ff4c
         'OCP\\Contacts\\ContactsMenu\\IProvider' => __DIR__ . '/../../..' . '/lib/public/Contacts/ContactsMenu/IProvider.php',
         'OCP\\Contacts\\Events\\ContactInteractedWithEvent' => __DIR__ . '/../../..' . '/lib/public/Contacts/Events/ContactInteractedWithEvent.php',
         'OCP\\Contacts\\IManager' => __DIR__ . '/../../..' . '/lib/public/Contacts/IManager.php',
+        'OCP\\DB\\IPreparedStatement' => __DIR__ . '/../../..' . '/lib/public/DB/IPreparedStatement.php',
+        'OCP\\DB\\IResult' => __DIR__ . '/../../..' . '/lib/public/DB/IResult.php',
         'OCP\\DB\\ISchemaWrapper' => __DIR__ . '/../../..' . '/lib/public/DB/ISchemaWrapper.php',
         'OCP\\DB\\QueryBuilder\\ICompositeExpression' => __DIR__ . '/../../..' . '/lib/public/DB/QueryBuilder/ICompositeExpression.php',
         'OCP\\DB\\QueryBuilder\\IExpressionBuilder' => __DIR__ . '/../../..' . '/lib/public/DB/QueryBuilder/IExpressionBuilder.php',
@@ -977,10 +979,10 @@ class ComposerStaticInit53792487c5a8370acc0b06b1a864ff4c
         'OC\\DB\\AdapterPgSql' => __DIR__ . '/../../..' . '/lib/private/DB/AdapterPgSql.php',
         'OC\\DB\\AdapterSqlite' => __DIR__ . '/../../..' . '/lib/private/DB/AdapterSqlite.php',
         'OC\\DB\\Connection' => __DIR__ . '/../../..' . '/lib/private/DB/Connection.php',
+        'OC\\DB\\ConnectionAdapter' => __DIR__ . '/../../..' . '/lib/private/DB/ConnectionAdapter.php',
         'OC\\DB\\ConnectionFactory' => __DIR__ . '/../../..' . '/lib/private/DB/ConnectionFactory.php',
         'OC\\DB\\MDB2SchemaManager' => __DIR__ . '/../../..' . '/lib/private/DB/MDB2SchemaManager.php',
         'OC\\DB\\MDB2SchemaReader' => __DIR__ . '/../../..' . '/lib/private/DB/MDB2SchemaReader.php',
-        'OC\\DB\\MDB2SchemaWriter' => __DIR__ . '/../../..' . '/lib/private/DB/MDB2SchemaWriter.php',
         'OC\\DB\\MigrationException' => __DIR__ . '/../../..' . '/lib/private/DB/MigrationException.php',
         'OC\\DB\\MigrationService' => __DIR__ . '/../../..' . '/lib/private/DB/MigrationService.php',
         'OC\\DB\\Migrator' => __DIR__ . '/../../..' . '/lib/private/DB/Migrator.php',
@@ -994,6 +996,7 @@ class ComposerStaticInit53792487c5a8370acc0b06b1a864ff4c
         'OC\\DB\\OracleMigrator' => __DIR__ . '/../../..' . '/lib/private/DB/OracleMigrator.php',
         'OC\\DB\\PgSqlTools' => __DIR__ . '/../../..' . '/lib/private/DB/PgSqlTools.php',
         'OC\\DB\\PostgreSqlMigrator' => __DIR__ . '/../../..' . '/lib/private/DB/PostgreSqlMigrator.php',
+        'OC\\DB\\PreparedStatement' => __DIR__ . '/../../..' . '/lib/private/DB/PreparedStatement.php',
         'OC\\DB\\QueryBuilder\\CompositeExpression' => __DIR__ . '/../../..' . '/lib/private/DB/QueryBuilder/CompositeExpression.php',
         'OC\\DB\\QueryBuilder\\ExpressionBuilder\\ExpressionBuilder' => __DIR__ . '/../../..' . '/lib/private/DB/QueryBuilder/ExpressionBuilder/ExpressionBuilder.php',
         'OC\\DB\\QueryBuilder\\ExpressionBuilder\\MySqlExpressionBuilder' => __DIR__ . '/../../..' . '/lib/private/DB/QueryBuilder/ExpressionBuilder/MySqlExpressionBuilder.php',
@@ -1010,6 +1013,7 @@ class ComposerStaticInit53792487c5a8370acc0b06b1a864ff4c
         'OC\\DB\\QueryBuilder\\QueryFunction' => __DIR__ . '/../../..' . '/lib/private/DB/QueryBuilder/QueryFunction.php',
         'OC\\DB\\QueryBuilder\\QuoteHelper' => __DIR__ . '/../../..' . '/lib/private/DB/QueryBuilder/QuoteHelper.php',
         'OC\\DB\\ReconnectWrapper' => __DIR__ . '/../../..' . '/lib/private/DB/ReconnectWrapper.php',
+        'OC\\DB\\ResultAdapter' => __DIR__ . '/../../..' . '/lib/private/DB/ResultAdapter.php',
         'OC\\DB\\SQLiteMigrator' => __DIR__ . '/../../..' . '/lib/private/DB/SQLiteMigrator.php',
         'OC\\DB\\SQLiteSessionInit' => __DIR__ . '/../../..' . '/lib/private/DB/SQLiteSessionInit.php',
         'OC\\DB\\SchemaWrapper' => __DIR__ . '/../../..' . '/lib/private/DB/SchemaWrapper.php',
diff --git a/lib/private/AppConfig.php b/lib/private/AppConfig.php
index 84305e60a12..6a0dc2fab2b 100644
--- a/lib/private/AppConfig.php
+++ b/lib/private/AppConfig.php
@@ -33,10 +33,10 @@
 
 namespace OC;
 
+use OC\DB\Connection;
 use OC\DB\OracleConnection;
 use OCP\IAppConfig;
 use OCP\IConfig;
-use OCP\IDBConnection;
 
 /**
  * This class provides an easy way for apps to store config values in the
@@ -68,7 +68,7 @@ class AppConfig implements IAppConfig {
 		],
 	];
 
-	/** @var \OCP\IDBConnection */
+	/** @var Connection */
 	protected $conn;
 
 	/** @var array[] */
@@ -78,11 +78,10 @@ class AppConfig implements IAppConfig {
 	private $configLoaded = false;
 
 	/**
-	 * @param IDBConnection $conn
+	 * @param Connection $conn
 	 */
-	public function __construct(IDBConnection $conn) {
+	public function __construct(Connection $conn) {
 		$this->conn = $conn;
-		$this->configLoaded = false;
 	}
 
 	/**
diff --git a/lib/private/AppFramework/Http/Dispatcher.php b/lib/private/AppFramework/Http/Dispatcher.php
index 47e6650c999..828864f1e02 100644
--- a/lib/private/AppFramework/Http/Dispatcher.php
+++ b/lib/private/AppFramework/Http/Dispatcher.php
@@ -36,12 +36,11 @@ namespace OC\AppFramework\Http;
 use OC\AppFramework\Http;
 use OC\AppFramework\Middleware\MiddlewareDispatcher;
 use OC\AppFramework\Utility\ControllerMethodReflector;
-use OC\DB\Connection;
+use OC\DB\ConnectionAdapter;
 use OCP\AppFramework\Controller;
 use OCP\AppFramework\Http\DataResponse;
 use OCP\AppFramework\Http\Response;
 use OCP\IConfig;
-use OCP\IDBConnection;
 use OCP\IRequest;
 use Psr\Log\LoggerInterface;
 
@@ -65,7 +64,7 @@ class Dispatcher {
 	/** @var IConfig */
 	private $config;
 
-	/** @var IDBConnection|Connection */
+	/** @var ConnectionAdapter */
 	private $connection;
 
 	/** @var LoggerInterface */
@@ -79,7 +78,7 @@ class Dispatcher {
 	 * the arguments for the controller
 	 * @param IRequest $request the incoming request
 	 * @param IConfig $config
-	 * @param IDBConnection $connection
+	 * @param ConnectionAdapter $connection
 	 * @param LoggerInterface $logger
 	 */
 	public function __construct(Http $protocol,
@@ -87,7 +86,7 @@ class Dispatcher {
 								ControllerMethodReflector $reflector,
 								IRequest $request,
 								IConfig $config,
-								IDBConnection $connection,
+								ConnectionAdapter $connection,
 								LoggerInterface $logger) {
 		$this->protocol = $protocol;
 		$this->middlewareDispatcher = $middlewareDispatcher;
@@ -122,13 +121,13 @@ class Dispatcher {
 
 			$databaseStatsBefore = [];
 			if ($this->config->getSystemValueBool('debug', false)) {
-				$databaseStatsBefore = $this->connection->getStats();
+				$databaseStatsBefore = $this->connection->getInner()->getStats();
 			}
 
 			$response = $this->executeController($controller, $methodName);
 
 			if (!empty($databaseStatsBefore)) {
-				$databaseStatsAfter = $this->connection->getStats();
+				$databaseStatsAfter = $this->connection->getInner()->getStats();
 				$numBuilt = $databaseStatsAfter['built'] - $databaseStatsBefore['built'];
 				$numExecuted = $databaseStatsAfter['executed'] - $databaseStatsBefore['executed'];
 
diff --git a/lib/private/DB/Adapter.php b/lib/private/DB/Adapter.php
index 26fd018dec1..49b831301be 100644
--- a/lib/private/DB/Adapter.php
+++ b/lib/private/DB/Adapter.php
@@ -52,7 +52,7 @@ class Adapter {
 	 * @return int id of last insert statement
 	 */
 	public function lastInsertId($table) {
-		return $this->conn->realLastInsertId($table);
+		return (int) $this->conn->realLastInsertId($table);
 	}
 
 	/**
@@ -94,7 +94,7 @@ class Adapter {
 	 *				If this is null or an empty array, all keys of $input will be compared
 	 *				Please note: text fields (clob) must not be used in the compare array
 	 * @return int number of inserted rows
-	 * @throws \Doctrine\DBAL\DBALException
+	 * @throws \Doctrine\DBAL\Exception
 	 * @deprecated 15.0.0 - use unique index and "try { $db->insert() } catch (UniqueConstraintViolationException $e) {}" instead, because it is more reliable and does not have the risk for deadlocks - see https://github.com/nextcloud/server/pull/12371
 	 */
 	public function insertIfNotExist($table, $input, array $compare = null) {
diff --git a/lib/private/DB/AdapterPgSql.php b/lib/private/DB/AdapterPgSql.php
index 77f0b6b7722..0d8794d59ac 100644
--- a/lib/private/DB/AdapterPgSql.php
+++ b/lib/private/DB/AdapterPgSql.php
@@ -31,7 +31,10 @@ class AdapterPgSql extends Adapter {
 	protected $compatModePre9_5 = null;
 
 	public function lastInsertId($table) {
-		return $this->conn->fetchColumn('SELECT lastval()');
+		$result = $this->conn->executeQuery('SELECT lastval()');
+		$val = $result->fetchOne();
+		$result->free();
+		return (int)$val;
 	}
 
 	public const UNIX_TIMESTAMP_REPLACEMENT = 'cast(extract(epoch from current_timestamp) as integer)';
@@ -62,7 +65,9 @@ class AdapterPgSql extends Adapter {
 			return $this->compatModePre9_5;
 		}
 
-		$version = $this->conn->fetchColumn('SHOW SERVER_VERSION');
+		$result = $this->conn->executeQuery('SHOW SERVER_VERSION');
+		$version = $result->fetchOne();
+		$result->free();
 		$this->compatModePre9_5 = version_compare($version, '9.5', '<');
 
 		return $this->compatModePre9_5;
diff --git a/lib/private/DB/AdapterSqlite.php b/lib/private/DB/AdapterSqlite.php
index 5731ee1721a..a62960bae1a 100644
--- a/lib/private/DB/AdapterSqlite.php
+++ b/lib/private/DB/AdapterSqlite.php
@@ -62,7 +62,7 @@ class AdapterSqlite extends Adapter {
 	 *				If this is null or an empty array, all keys of $input will be compared
 	 *				Please note: text fields (clob) must not be used in the compare array
 	 * @return int number of inserted rows
-	 * @throws \Doctrine\DBAL\DBALException
+	 * @throws \Doctrine\DBAL\Exception
 	 * @deprecated 15.0.0 - use unique index and "try { $db->insert() } catch (UniqueConstraintViolationException $e) {}" instead, because it is more reliable and does not have the risk for deadlocks - see https://github.com/nextcloud/server/pull/12371
 	 */
 	public function insertIfNotExist($table, $input, array $compare = null) {
diff --git a/lib/private/DB/Connection.php b/lib/private/DB/Connection.php
index b024989ac04..c67c6df0826 100644
--- a/lib/private/DB/Connection.php
+++ b/lib/private/DB/Connection.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 /**
  * @copyright Copyright (c) 2016, ownCloud, Inc.
  *
@@ -36,20 +39,21 @@ namespace OC\DB;
 use Doctrine\Common\EventManager;
 use Doctrine\DBAL\Cache\QueryCacheProfile;
 use Doctrine\DBAL\Configuration;
-use Doctrine\DBAL\DBALException;
 use Doctrine\DBAL\Driver;
+use Doctrine\DBAL\Exception;
 use Doctrine\DBAL\Exception\ConstraintViolationException;
 use Doctrine\DBAL\Exception\NotNullConstraintViolationException;
-use Doctrine\DBAL\Platforms\MySqlPlatform;
+use Doctrine\DBAL\Platforms\MySQLPlatform;
+use Doctrine\DBAL\Result;
 use Doctrine\DBAL\Schema\Schema;
+use Doctrine\DBAL\Statement;
 use OC\DB\QueryBuilder\QueryBuilder;
 use OC\SystemConfig;
 use OCP\DB\QueryBuilder\IQueryBuilder;
-use OCP\IDBConnection;
 use OCP\ILogger;
 use OCP\PreConditionNotMetException;
 
-class Connection extends ReconnectWrapper implements IDBConnection {
+class Connection extends ReconnectWrapper {
 	/** @var string */
 	protected $tablePrefix;
 
@@ -73,9 +77,9 @@ class Connection extends ReconnectWrapper implements IDBConnection {
 	public function connect() {
 		try {
 			return parent::connect();
-		} catch (DBALException $e) {
+		} catch (Exception $e) {
 			// throw a new exception to prevent leaking info from the stacktrace
-			throw new DBALException('Failed to connect to the database: ' . $e->getMessage(), $e->getCode());
+			throw new Exception('Failed to connect to the database: ' . $e->getMessage(), $e->getCode());
 		}
 	}
 
@@ -88,13 +92,11 @@ class Connection extends ReconnectWrapper implements IDBConnection {
 
 	/**
 	 * Returns a QueryBuilder for the connection.
-	 *
-	 * @return \OCP\DB\QueryBuilder\IQueryBuilder
 	 */
-	public function getQueryBuilder() {
+	public function getQueryBuilder(): IQueryBuilder {
 		$this->queriesBuilt++;
 		return new QueryBuilder(
-			$this,
+			new ConnectionAdapter($this),
 			$this->systemConfig,
 			$this->logger
 		);
@@ -181,9 +183,9 @@ class Connection extends ReconnectWrapper implements IDBConnection {
 	 * @param string $statement The SQL statement to prepare.
 	 * @param int $limit
 	 * @param int $offset
-	 * @return \Doctrine\DBAL\Driver\Statement The prepared statement.
+	 * @return Statement The prepared statement.
 	 */
-	public function prepare($statement, $limit = null, $offset = null) {
+	public function prepare($statement, $limit = null, $offset = null): Statement {
 		if ($limit === -1) {
 			$limit = null;
 		}
@@ -208,18 +210,18 @@ class Connection extends ReconnectWrapper implements IDBConnection {
 	 * @param array                                       $types  The types the previous parameters are in.
 	 * @param \Doctrine\DBAL\Cache\QueryCacheProfile|null $qcp    The query cache profile, optional.
 	 *
-	 * @return \Doctrine\DBAL\Driver\Statement The executed statement.
+	 * @return Result The executed statement.
 	 *
-	 * @throws \Doctrine\DBAL\DBALException
+	 * @throws \Doctrine\DBAL\Exception
 	 */
-	public function executeQuery($sql, array $params = [], $types = [], QueryCacheProfile $qcp = null) {
+	public function executeQuery(string $sql, array $params = [], $types = [], QueryCacheProfile $qcp = null): Result {
 		$sql = $this->replaceTablePrefix($sql);
 		$sql = $this->adapter->fixupStatement($sql);
 		$this->queriesExecuted++;
 		return parent::executeQuery($sql, $params, $types, $qcp);
 	}
 
-	public function executeUpdate($sql, array $params = [], array $types = []) {
+	public function executeUpdate(string $sql, array $params = [], array $types = []): int {
 		$sql = $this->replaceTablePrefix($sql);
 		$sql = $this->adapter->fixupStatement($sql);
 		$this->queriesExecuted++;
@@ -236,11 +238,11 @@ class Connection extends ReconnectWrapper implements IDBConnection {
 	 * @param array  $params The query parameters.
 	 * @param array  $types  The parameter types.
 	 *
-	 * @return integer The number of affected rows.
+	 * @return int The number of affected rows.
 	 *
-	 * @throws \Doctrine\DBAL\DBALException
+	 * @throws \Doctrine\DBAL\Exception
 	 */
-	public function executeStatement($sql, array $params = [], array $types = []) {
+	public function executeStatement($sql, array $params = [], array $types = []): int {
 		$sql = $this->replaceTablePrefix($sql);
 		$sql = $this->adapter->fixupStatement($sql);
 		$this->queriesExecuted++;
@@ -256,7 +258,7 @@ class Connection extends ReconnectWrapper implements IDBConnection {
 	 * columns or sequences.
 	 *
 	 * @param string $seqName Name of the sequence object from which the ID should be returned.
-	 * @return string A string representation of the last inserted ID.
+	 * @return string the last inserted ID.
 	 */
 	public function lastInsertId($seqName = null) {
 		if ($seqName) {
@@ -281,7 +283,7 @@ class Connection extends ReconnectWrapper implements IDBConnection {
 	 *				If this is null or an empty array, all keys of $input will be compared
 	 *				Please note: text fields (clob) must not be used in the compare array
 	 * @return int number of inserted rows
-	 * @throws \Doctrine\DBAL\DBALException
+	 * @throws \Doctrine\DBAL\Exception
 	 * @deprecated 15.0.0 - use unique index and "try { $db->insert() } catch (UniqueConstraintViolationException $e) {}" instead, because it is more reliable and does not have the risk for deadlocks - see https://github.com/nextcloud/server/pull/12371
 	 */
 	public function insertIfNotExist($table, $input, array $compare = null) {
@@ -310,7 +312,7 @@ class Connection extends ReconnectWrapper implements IDBConnection {
 	 * @param array $values (column name => value)
 	 * @param array $updatePreconditionValues ensure values match preconditions (column name => value)
 	 * @return int number of new rows
-	 * @throws \Doctrine\DBAL\DBALException
+	 * @throws \Doctrine\DBAL\Exception
 	 * @throws PreConditionNotMetException
 	 */
 	public function setValues($table, array $keys, array $values, array $updatePreconditionValues = []) {
@@ -393,7 +395,7 @@ class Connection extends ReconnectWrapper implements IDBConnection {
 	public function getError() {
 		$msg = $this->errorCode() . ': ';
 		$errorInfo = $this->errorInfo();
-		if (is_array($errorInfo)) {
+		if (!empty($errorInfo)) {
 			$msg .= 'SQLSTATE = '.$errorInfo[0] . ', ';
 			$msg .= 'Driver Code = '.$errorInfo[1] . ', ';
 			$msg .= 'Driver Message = '.$errorInfo[2];
@@ -401,6 +403,14 @@ class Connection extends ReconnectWrapper implements IDBConnection {
 		return $msg;
 	}
 
+	public function errorCode() {
+		return -1;
+	}
+
+	public function errorInfo() {
+		return [];
+	}
+
 	/**
 	 * Drop a table from the database if it exists
 	 *
@@ -462,7 +472,7 @@ class Connection extends ReconnectWrapper implements IDBConnection {
 	 * @since 11.0.0
 	 */
 	public function supports4ByteText() {
-		if (!$this->getDatabasePlatform() instanceof MySqlPlatform) {
+		if (!$this->getDatabasePlatform() instanceof MySQLPlatform) {
 			return true;
 		}
 		return $this->getParams()['charset'] === 'utf8mb4';
diff --git a/lib/private/DB/ConnectionAdapter.php b/lib/private/DB/ConnectionAdapter.php
new file mode 100644
index 00000000000..97a0b60044d
--- /dev/null
+++ b/lib/private/DB/ConnectionAdapter.php
@@ -0,0 +1,172 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * @copyright 2020 Christoph Wurst <christoph@winzerhof-wurst.at>
+ *
+ * @author 2020 Christoph Wurst <christoph@winzerhof-wurst.at>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace OC\DB;
+
+use Doctrine\DBAL\Platforms\AbstractPlatform;
+use Doctrine\DBAL\Schema\Schema;
+use OCP\DB\IPreparedStatement;
+use OCP\DB\IResult;
+use OCP\DB\QueryBuilder\IQueryBuilder;
+use OCP\IDBConnection;
+
+/**
+ * Adapts the public API to our internal DBAL connection wrapper
+ */
+class ConnectionAdapter implements IDBConnection {
+
+	/** @var Connection */
+	private $inner;
+
+	public function __construct(Connection $inner) {
+		$this->inner = $inner;
+	}
+
+	public function getQueryBuilder(): IQueryBuilder {
+		return $this->inner->getQueryBuilder();
+	}
+
+	public function prepare($sql, $limit = null, $offset = null): IPreparedStatement {
+		return new PreparedStatement(
+			$this->inner->prepare($sql, $limit, $offset)
+		);
+	}
+
+	public function executeQuery(string $sql, array $params = [], $types = []): IResult {
+		return new ResultAdapter(
+			$this->inner->executeQuery($sql, $params, $types)
+		);
+	}
+
+	public function executeUpdate(string $sql, array $params = [], array $types = []): int {
+		return $this->inner->executeUpdate($sql, $params, $types);
+	}
+
+	public function executeStatement($sql, array $params = [], array $types = []): int {
+		return $this->inner->executeStatement($sql, $params, $types);
+	}
+
+	public function lastInsertId(string $table): int {
+		return (int) $this->inner->lastInsertId($table);
+	}
+
+	public function insertIfNotExist(string $table, array $input, array $compare = null) {
+		return $this->inner->insertIfNotExist($table, $input, $compare);
+	}
+
+	public function insertIgnoreConflict(string $table, array $values): int {
+		return $this->inner->insertIgnoreConflict($table, $values);
+	}
+
+	public function setValues($table, array $keys, array $values, array $updatePreconditionValues = []): int {
+		return $this->inner->setValues($table, $keys, $values, $updatePreconditionValues);
+	}
+
+	public function lockTable($tableName): void {
+		$this->inner->lockTable($tableName);
+	}
+
+	public function unlockTable(): void {
+		$this->inner->unlockTable();
+	}
+
+	public function beginTransaction(): void {
+		$this->inner->beginTransaction();
+	}
+
+	public function inTransaction(): bool {
+		return $this->inner->inTransaction();
+	}
+
+	public function commit(): void {
+		$this->inner->commit();
+	}
+
+	public function rollBack(): void {
+		$this->inner->rollBack();
+	}
+
+	public function getError(): string {
+		return $this->inner->getError();
+	}
+
+	public function errorCode() {
+		return $this->inner->errorCode();
+	}
+
+	public function errorInfo() {
+		return $this->inner->errorInfo();
+	}
+
+	public function connect(): bool {
+		return $this->inner->connect();
+	}
+
+	public function close(): void {
+		$this->inner->close();
+	}
+
+	public function quote($input, $type = IQueryBuilder::PARAM_STR) {
+		return $this->inner->quote($input, $type);
+	}
+
+	/**
+	 * @todo we are leaking a 3rdparty type here
+	 */
+	public function getDatabasePlatform(): AbstractPlatform {
+		return $this->inner->getDatabasePlatform();
+	}
+
+	public function dropTable(string $table): void {
+		$this->inner->dropTable($table);
+	}
+
+	public function tableExists(string $table): bool {
+		return $this->inner->tableExists($table);
+	}
+
+	public function escapeLikeParameter(string $param): string {
+		return $this->inner->escapeLikeParameter($param);
+	}
+
+	public function supports4ByteText(): bool {
+		return $this->inner->supports4ByteText();
+	}
+
+	/**
+	 * @todo leaks a 3rdparty type
+	 */
+	public function createSchema(): Schema {
+		return $this->inner->createSchema();
+	}
+
+	public function migrateToSchema(Schema $toSchema): void {
+		$this->inner->migrateToSchema($toSchema);
+	}
+
+	public function getInner(): Connection {
+		return $this->inner;
+	}
+}
diff --git a/lib/private/DB/MDB2SchemaManager.php b/lib/private/DB/MDB2SchemaManager.php
index 44ea3986214..18549eb1fa2 100644
--- a/lib/private/DB/MDB2SchemaManager.php
+++ b/lib/private/DB/MDB2SchemaManager.php
@@ -31,36 +31,24 @@
 
 namespace OC\DB;
 
-use Doctrine\DBAL\Platforms\MySqlPlatform;
+use Doctrine\DBAL\Platforms\MySQLPlatform;
 use Doctrine\DBAL\Platforms\OraclePlatform;
-use Doctrine\DBAL\Platforms\PostgreSqlPlatform;
+use Doctrine\DBAL\Platforms\PostgreSQL94Platform;
 use Doctrine\DBAL\Platforms\SqlitePlatform;
 use Doctrine\DBAL\Schema\Schema;
-use OCP\IDBConnection;
 
 class MDB2SchemaManager {
-	/** @var \OC\DB\Connection $conn */
+	/** @var Connection $conn */
 	protected $conn;
 
 	/**
-	 * @param IDBConnection $conn
+	 * @param Connection $conn
 	 */
 	public function __construct($conn) {
 		$this->conn = $conn;
 	}
 
 	/**
-	 * saves database scheme to xml file
-	 * @param string $file name of file
-	 * @return bool
-	 *
-	 * TODO: write more documentation
-	 */
-	public function getDbStructure($file) {
-		return \OC\DB\MDB2SchemaWriter::saveSchemaToFile($file, $this->conn);
-	}
-
-	/**
 	 * Creates tables from XML file
 	 * @param string $file file to read structure from
 	 * @return bool
@@ -86,9 +74,9 @@ class MDB2SchemaManager {
 			return new SQLiteMigrator($this->conn, $random, $config, $dispatcher);
 		} elseif ($platform instanceof OraclePlatform) {
 			return new OracleMigrator($this->conn, $random, $config, $dispatcher);
-		} elseif ($platform instanceof MySqlPlatform) {
+		} elseif ($platform instanceof MySQLPlatform) {
 			return new MySQLMigrator($this->conn, $random, $config, $dispatcher);
-		} elseif ($platform instanceof PostgreSqlPlatform) {
+		} elseif ($platform instanceof PostgreSQL94Platform) {
 			return new PostgreSqlMigrator($this->conn, $random, $config, $dispatcher);
 		} else {
 			return new Migrator($this->conn, $random, $config, $dispatcher);
diff --git a/lib/private/DB/MDB2SchemaReader.php b/lib/private/DB/MDB2SchemaReader.php
index abf58ffa053..687438495b1 100644
--- a/lib/private/DB/MDB2SchemaReader.php
+++ b/lib/private/DB/MDB2SchemaReader.php
@@ -260,8 +260,16 @@ class MDB2SchemaReader {
 				$options['primary'] = true;
 			}
 
-			$table->addColumn($name, $type, $options);
+			# not used anymore in the options argument
+			# see https://github.com/doctrine/dbal/commit/138eb85234a1faeaa2e6a32cd7bcc66bb51c64e8#diff-300f55366adb50a32a40882ebdc95c163b141f64cba5f45f20bda04a907b3eb3L82
+			# therefore it's read before and then unset right before the addColumn call
+			$setPrimaryKey = false;
 			if (!empty($options['primary']) && $options['primary']) {
+				$setPrimaryKey = true;
+			}
+			unset($options['primary']);
+			$table->addColumn($name, $type, $options);
+			if ($setPrimaryKey) {
 				$table->setPrimaryKey([$name]);
 			}
 		}
diff --git a/lib/private/DB/MDB2SchemaWriter.php b/lib/private/DB/MDB2SchemaWriter.php
deleted file mode 100644
index 2c1f6a5e545..00000000000
--- a/lib/private/DB/MDB2SchemaWriter.php
+++ /dev/null
@@ -1,181 +0,0 @@
-<?php
-/**
- * @copyright Copyright (c) 2016, ownCloud, Inc.
- *
- * @author Bart Visscher <bartv@thisnet.nl>
- * @author Christoph Wurst <christoph@winzerhof-wurst.at>
- * @author Jörn Friedrich Dreyer <jfd@butonic.de>
- * @author Morris Jobke <hey@morrisjobke.de>
- * @author tbelau666 <thomas.belau@gmx.de>
- * @author Thomas Müller <thomas.mueller@tmit.eu>
- *
- * @license AGPL-3.0
- *
- * This code is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License, version 3,
- * as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License, version 3,
- * along with this program. If not, see <http://www.gnu.org/licenses/>
- *
- */
-
-namespace OC\DB;
-
-use Doctrine\DBAL\Schema\Column;
-use Doctrine\DBAL\Schema\Index;
-
-class MDB2SchemaWriter {
-
-	/**
-	 * @param string $file
-	 * @param \OC\DB\Connection $conn
-	 * @return bool
-	 */
-	public static function saveSchemaToFile($file, \OC\DB\Connection $conn) {
-		$config = \OC::$server->getConfig();
-
-		$xml = new \SimpleXMLElement('<database/>');
-		$xml->addChild('name', $config->getSystemValue('dbname', 'owncloud'));
-		$xml->addChild('create', 'true');
-		$xml->addChild('overwrite', 'false');
-		if ($config->getSystemValue('dbtype', 'sqlite') === 'mysql' && $config->getSystemValue('mysql.utf8mb4', false)) {
-			$xml->addChild('charset', 'utf8mb4');
-		} else {
-			$xml->addChild('charset', 'utf8');
-		}
-
-		// FIX ME: bloody work around
-		if ($config->getSystemValue('dbtype', 'sqlite') === 'oci') {
-			$filterExpression = '/^"' . preg_quote($conn->getPrefix()) . '/';
-		} else {
-			$filterExpression = '/^' . preg_quote($conn->getPrefix()) . '/';
-		}
-		$conn->getConfiguration()->setFilterSchemaAssetsExpression($filterExpression);
-
-		foreach ($conn->getSchemaManager()->listTables() as $table) {
-			self::saveTable($table, $xml->addChild('table'));
-		}
-		file_put_contents($file, $xml->asXML());
-		return true;
-	}
-
-	/**
-	 * @param \Doctrine\DBAL\Schema\Table $table
-	 * @param \SimpleXMLElement $xml
-	 */
-	private static function saveTable($table, $xml) {
-		$xml->addChild('name', $table->getName());
-		$declaration = $xml->addChild('declaration');
-		foreach ($table->getColumns() as $column) {
-			self::saveColumn($column, $declaration->addChild('field'));
-		}
-		foreach ($table->getIndexes() as $index) {
-			if ($index->getName() == 'PRIMARY') {
-				$autoincrement = false;
-				foreach ($index->getColumns() as $column) {
-					if ($table->getColumn($column)->getAutoincrement()) {
-						$autoincrement = true;
-					}
-				}
-				if ($autoincrement) {
-					continue;
-				}
-			}
-			self::saveIndex($index, $declaration->addChild('index'));
-		}
-	}
-
-	/**
-	 * @param Column $column
-	 * @param \SimpleXMLElement $xml
-	 */
-	private static function saveColumn($column, $xml) {
-		$xml->addChild('name', $column->getName());
-		switch ($column->getType()) {
-			case 'SmallInt':
-			case 'Integer':
-			case 'BigInt':
-				$xml->addChild('type', 'integer');
-				$default = $column->getDefault();
-				if (is_null($default) && $column->getAutoincrement()) {
-					$default = '0';
-				}
-				$xml->addChild('default', $default);
-				$xml->addChild('notnull', self::toBool($column->getNotnull()));
-				if ($column->getAutoincrement()) {
-					$xml->addChild('autoincrement', '1');
-				}
-				if ($column->getUnsigned()) {
-					$xml->addChild('unsigned', 'true');
-				}
-				$length = '4';
-				if ($column->getType() == 'SmallInt') {
-					$length = '2';
-				} elseif ($column->getType() == 'BigInt') {
-					$length = '8';
-				}
-				$xml->addChild('length', $length);
-				break;
-			case 'String':
-				$xml->addChild('type', 'text');
-				$default = trim($column->getDefault());
-				if ($default === '') {
-					$default = false;
-				}
-				$xml->addChild('default', $default);
-				$xml->addChild('notnull', self::toBool($column->getNotnull()));
-				$xml->addChild('length', $column->getLength());
-				break;
-			case 'Text':
-				$xml->addChild('type', 'clob');
-				$xml->addChild('notnull', self::toBool($column->getNotnull()));
-				break;
-			case 'Decimal':
-				$xml->addChild('type', 'decimal');
-				$xml->addChild('default', $column->getDefault());
-				$xml->addChild('notnull', self::toBool($column->getNotnull()));
-				$xml->addChild('length', '15');
-				break;
-			case 'Boolean':
-				$xml->addChild('type', 'integer');
-				$xml->addChild('default', $column->getDefault());
-				$xml->addChild('notnull', self::toBool($column->getNotnull()));
-				$xml->addChild('length', '1');
-				break;
-			case 'DateTime':
-				$xml->addChild('type', 'timestamp');
-				$xml->addChild('default', $column->getDefault());
-				$xml->addChild('notnull', self::toBool($column->getNotnull()));
-				break;
-
-		}
-	}
-
-	/**
-	 * @param Index $index
-	 * @param \SimpleXMLElement $xml
-	 */
-	private static function saveIndex($index, $xml) {
-		$xml->addChild('name', $index->getName());
-		if ($index->isPrimary()) {
-			$xml->addChild('primary', 'true');
-		} elseif ($index->isUnique()) {
-			$xml->addChild('unique', 'true');
-		}
-		foreach ($index->getColumns() as $column) {
-			$field = $xml->addChild('field');
-			$field->addChild('name', $column);
-			$field->addChild('sorting', 'ascending');
-		}
-	}
-
-	private static function toBool($bool) {
-		return $bool ? 'true' : 'false';
-	}
-}
diff --git a/lib/private/DB/MigrationService.php b/lib/private/DB/MigrationService.php
index 6a1cb4be016..44707911092 100644
--- a/lib/private/DB/MigrationService.php
+++ b/lib/private/DB/MigrationService.php
@@ -30,7 +30,7 @@ namespace OC\DB;
 
 use Doctrine\DBAL\Exception\DriverException;
 use Doctrine\DBAL\Platforms\OraclePlatform;
-use Doctrine\DBAL\Platforms\PostgreSqlPlatform;
+use Doctrine\DBAL\Platforms\PostgreSQL94Platform;
 use Doctrine\DBAL\Schema\Index;
 use Doctrine\DBAL\Schema\Schema;
 use Doctrine\DBAL\Schema\SchemaException;
@@ -42,7 +42,6 @@ use OC\IntegrityCheck\Helpers\AppLocator;
 use OC\Migration\SimpleOutput;
 use OCP\AppFramework\App;
 use OCP\AppFramework\QueryException;
-use OCP\IDBConnection;
 use OCP\Migration\IMigrationStep;
 use OCP\Migration\IOutput;
 
@@ -65,12 +64,12 @@ class MigrationService {
 	 * MigrationService constructor.
 	 *
 	 * @param $appName
-	 * @param IDBConnection $connection
+	 * @param Connection $connection
 	 * @param AppLocator $appLocator
 	 * @param IOutput|null $output
 	 * @throws \Exception
 	 */
-	public function __construct($appName, IDBConnection $connection, IOutput $output = null, AppLocator $appLocator = null) {
+	public function __construct($appName, Connection $connection, IOutput $output = null, AppLocator $appLocator = null) {
 		$this->appName = $appName;
 		$this->connection = $connection;
 		$this->output = $output;
@@ -591,7 +590,7 @@ class MigrationService {
 				$indexName = strtolower($primaryKey->getName());
 				$isUsingDefaultName = $indexName === 'primary';
 
-				if ($this->connection->getDatabasePlatform() instanceof PostgreSqlPlatform) {
+				if ($this->connection->getDatabasePlatform() instanceof PostgreSQL94Platform) {
 					$defaultName = $table->getName() . '_pkey';
 					$isUsingDefaultName = strtolower($defaultName) === $indexName;
 
diff --git a/lib/private/DB/Migrator.php b/lib/private/DB/Migrator.php
index 569b1a6c282..f62735ea6b2 100644
--- a/lib/private/DB/Migrator.php
+++ b/lib/private/DB/Migrator.php
@@ -31,7 +31,8 @@
 
 namespace OC\DB;
 
-use Doctrine\DBAL\DBALException;
+use Doctrine\DBAL\Exception;
+use Doctrine\DBAL\Schema\AbstractAsset;
 use Doctrine\DBAL\Schema\Comparator;
 use Doctrine\DBAL\Schema\Index;
 use Doctrine\DBAL\Schema\Schema;
@@ -43,6 +44,7 @@ use OCP\IConfig;
 use OCP\Security\ISecureRandom;
 use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\EventDispatcher\GenericEvent;
+use function preg_match;
 
 class Migrator {
 
@@ -102,34 +104,6 @@ class Migrator {
 	}
 
 	/**
-	 * @param Schema $targetSchema
-	 * @throws \OC\DB\MigrationException
-	 */
-	public function checkMigrate(Schema $targetSchema) {
-		$this->noEmit = true;
-		/**@var \Doctrine\DBAL\Schema\Table[] $tables */
-		$tables = $targetSchema->getTables();
-		$filterExpression = $this->getFilterExpression();
-		$this->connection->getConfiguration()->
-			setFilterSchemaAssetsExpression($filterExpression);
-		$existingTables = $this->connection->getSchemaManager()->listTableNames();
-
-		$step = 0;
-		foreach ($tables as $table) {
-			if (strpos($table->getName(), '.')) {
-				list(, $tableName) = explode('.', $table->getName());
-			} else {
-				$tableName = $table->getName();
-			}
-			$this->emitCheckStep($tableName, $step++, count($tables));
-			// don't need to check for new tables
-			if (array_search($tableName, $existingTables) !== false) {
-				$this->checkTableMigrate($table);
-			}
-		}
-	}
-
-	/**
 	 * Create a unique name for the temporary table
 	 *
 	 * @param string $name
@@ -160,7 +134,7 @@ class Migrator {
 		try {
 			$this->applySchema($schema);
 			$this->dropTable($tmpName);
-		} catch (DBALException $e) {
+		} catch (Exception $e) {
 			// pgsql needs to commit it's failed transaction before doing anything else
 			if ($this->connection->isTransactionActive()) {
 				$this->connection->commit();
@@ -193,12 +167,18 @@ class Migrator {
 		}
 
 		// foreign keys are not supported so we just set it to an empty array
-		return new Table($newName, $table->getColumns(), $newIndexes, [], 0, $table->getOptions());
+		return new Table($newName, $table->getColumns(), $newIndexes, [], [], $table->getOptions());
 	}
 
 	public function createSchema() {
-		$filterExpression = $this->getFilterExpression();
-		$this->connection->getConfiguration()->setFilterSchemaAssetsExpression($filterExpression);
+		$this->connection->getConfiguration()->setSchemaAssetsFilter(function ($asset) {
+			/** @var string|AbstractAsset $asset */
+			$filterExpression = $this->getFilterExpression();
+			if ($asset instanceof AbstractAsset) {
+				return preg_match($filterExpression, $asset->getName()) !== false;
+			}
+			return preg_match($filterExpression, $asset) !== false;
+		});
 		return $this->connection->getSchemaManager()->createSchema();
 	}
 
@@ -206,7 +186,6 @@ class Migrator {
 	 * @param Schema $targetSchema
 	 * @param \Doctrine\DBAL\Connection $connection
 	 * @return \Doctrine\DBAL\Schema\SchemaDiff
-	 * @throws DBALException
 	 */
 	protected function getDiff(Schema $targetSchema, \Doctrine\DBAL\Connection $connection) {
 		// adjust varchar columns with a length higher then getVarcharMaxLength to clob
@@ -221,8 +200,14 @@ class Migrator {
 			}
 		}
 
-		$filterExpression = $this->getFilterExpression();
-		$this->connection->getConfiguration()->setFilterSchemaAssetsExpression($filterExpression);
+		$this->connection->getConfiguration()->setSchemaAssetsFilter(function ($asset) {
+			/** @var string|AbstractAsset $asset */
+			$filterExpression = $this->getFilterExpression();
+			if ($asset instanceof AbstractAsset) {
+				return preg_match($filterExpression, $asset->getName()) !== false;
+			}
+			return preg_match($filterExpression, $asset) !== false;
+		});
 		$sourceSchema = $connection->getSchemaManager()->createSchema();
 
 		// remove tables we don't know about
diff --git a/lib/private/DB/MySqlTools.php b/lib/private/DB/MySqlTools.php
index 007388d5615..e738a2bd94a 100644
--- a/lib/private/DB/MySqlTools.php
+++ b/lib/private/DB/MySqlTools.php
@@ -32,7 +32,7 @@ use OCP\IDBConnection;
 class MySqlTools {
 
 	/**
-	 * @param Connection $connection
+	 * @param IDBConnection $connection
 	 * @return bool
 	 */
 	public function supports4ByteCharset(IDBConnection $connection) {
diff --git a/lib/private/DB/OracleMigrator.php b/lib/private/DB/OracleMigrator.php
index cad5390f092..7a327a42797 100644
--- a/lib/private/DB/OracleMigrator.php
+++ b/lib/private/DB/OracleMigrator.php
@@ -30,7 +30,7 @@
 
 namespace OC\DB;
 
-use Doctrine\DBAL\DBALException;
+use Doctrine\DBAL\Exception;
 use Doctrine\DBAL\Schema\Column;
 use Doctrine\DBAL\Schema\ColumnDiff;
 use Doctrine\DBAL\Schema\ForeignKeyConstraint;
@@ -113,7 +113,7 @@ class OracleMigrator extends Migrator {
 	 * @param Schema $targetSchema
 	 * @param \Doctrine\DBAL\Connection $connection
 	 * @return \Doctrine\DBAL\Schema\SchemaDiff
-	 * @throws DBALException
+	 * @throws Exception
 	 */
 	protected function getDiff(Schema $targetSchema, \Doctrine\DBAL\Connection $connection) {
 		$schemaDiff = parent::getDiff($targetSchema, $connection);
@@ -128,10 +128,10 @@ class OracleMigrator extends Migrator {
 				array_map(function (Index $index) {
 					return $this->quoteIndex($index);
 				}, $table->getIndexes()),
+				[],
 				array_map(function (ForeignKeyConstraint $fck) {
 					return $this->quoteForeignKeyConstraint($fck);
 				}, $table->getForeignKeys()),
-				0,
 				$table->getOptions()
 			);
 		}, $schemaDiff->newTables);
@@ -141,8 +141,8 @@ class OracleMigrator extends Migrator {
 				$this->connection->quoteIdentifier($table->getName()),
 				$table->getColumns(),
 				$table->getIndexes(),
+				[],
 				$table->getForeignKeys(),
-				0,
 				$table->getOptions()
 			);
 		}, $schemaDiff->removedTables);
diff --git a/lib/private/DB/PgSqlTools.php b/lib/private/DB/PgSqlTools.php
index 724344ac2a1..d555bfb391b 100644
--- a/lib/private/DB/PgSqlTools.php
+++ b/lib/private/DB/PgSqlTools.php
@@ -26,7 +26,10 @@
 
 namespace OC\DB;
 
+use Doctrine\DBAL\Schema\AbstractAsset;
 use OCP\IConfig;
+use function preg_match;
+use function preg_quote;
 
 /**
  * Various PostgreSQL specific helper functions.
@@ -50,20 +53,30 @@ class PgSqlTools {
 	 * @return null
 	 */
 	public function resynchronizeDatabaseSequences(Connection $conn) {
-		$filterExpression = '/^' . preg_quote($this->config->getSystemValue('dbtableprefix', 'oc_')) . '/';
 		$databaseName = $conn->getDatabase();
-		$conn->getConfiguration()->setFilterSchemaAssetsExpression($filterExpression);
+		$conn->getConfiguration()->setSchemaAssetsFilter(function ($asset) {
+			/** @var string|AbstractAsset $asset */
+			$filterExpression = '/^' . preg_quote($this->config->getSystemValue('dbtableprefix', 'oc_')) . '/';
+			if ($asset instanceof AbstractAsset) {
+				return preg_match($filterExpression, $asset->getName()) !== false;
+			}
+			return preg_match($filterExpression, $asset) !== false;
+		});
 
 		foreach ($conn->getSchemaManager()->listSequences() as $sequence) {
 			$sequenceName = $sequence->getName();
 			$sqlInfo = 'SELECT table_schema, table_name, column_name
 				FROM information_schema.columns
 				WHERE column_default = ? AND table_catalog = ?';
-			$sequenceInfo = $conn->fetchAssoc($sqlInfo, [
+			$result = $conn->executeQuery($sqlInfo, [
 				"nextval('$sequenceName'::regclass)",
 				$databaseName
 			]);
+			$sequenceInfo = $result->fetchAssociative();
+			$result->free();
+			/** @var string $tableName */
 			$tableName = $sequenceInfo['table_name'];
+			/** @var string $columnName */
 			$columnName = $sequenceInfo['column_name'];
 			$sqlMaxId = "SELECT MAX($columnName) FROM $tableName";
 			$sqlSetval = "SELECT setval('$sequenceName', ($sqlMaxId))";
diff --git a/lib/private/DB/PreparedStatement.php b/lib/private/DB/PreparedStatement.php
new file mode 100644
index 00000000000..f679576a428
--- /dev/null
+++ b/lib/private/DB/PreparedStatement.php
@@ -0,0 +1,101 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * @copyright 2021 Christoph Wurst <christoph@winzerhof-wurst.at>
+ *
+ * @author 2021 Christoph Wurst <christoph@winzerhof-wurst.at>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace OC\DB;
+
+use Doctrine\DBAL\Exception;
+use Doctrine\DBAL\ParameterType;
+use Doctrine\DBAL\Statement;
+use OCP\DB\IPreparedStatement;
+use OCP\DB\IResult;
+use PDO;
+
+/**
+ * Adapts our public API to what doctrine/dbal exposed with 2.6
+ *
+ * The old dbal statement had stateful methods e.g. to fetch data from an executed
+ * prepared statement. To provide backwards compatibility to apps we need to make
+ * this class stateful. As soon as those now deprecated exposed methods are gone,
+ * we can limit the API of this adapter to the methods that map to the direct dbal
+ * methods without much magic.
+ */
+class PreparedStatement implements IPreparedStatement {
+
+	/** @var Statement */
+	private $statement;
+
+	/** @var IResult|null */
+	private $result;
+
+	public function __construct(Statement $statement) {
+		$this->statement = $statement;
+	}
+
+	public function closeCursor(): bool {
+		$this->getResult()->closeCursor();
+
+		return true;
+	}
+
+	public function fetch(int $fetchMode = PDO::FETCH_ASSOC) {
+		return $this->getResult()->fetch($fetchMode);
+	}
+
+	public function fetchAll(int $fetchMode = PDO::FETCH_ASSOC): array {
+		return $this->getResult()->fetchAll($fetchMode);
+	}
+
+	public function fetchColumn() {
+		return $this->getResult()->fetchOne();
+	}
+
+	public function fetchOne() {
+		return $this->getResult()->fetchOne();
+	}
+
+	public function bindValue($param, $value, $type = ParameterType::STRING): bool {
+		return $this->statement->bindValue($param, $value, $type);
+	}
+
+	public function bindParam($param, &$variable, $type = ParameterType::STRING, $length = null): bool {
+		return $this->statement->bindParam($param, $variable, $type, $length);
+	}
+
+	public function execute($params = null): IResult {
+		return ($this->result = new ResultAdapter($this->statement->execute($params)));
+	}
+
+	public function rowCount(): int {
+		return $this->getResult()->rowCount();
+	}
+
+	private function getResult(): IResult {
+		if ($this->result !== null) {
+			return $this->result;
+		}
+
+		throw new Exception("You have to execute the prepared statement before accessing the results");
+	}
+}
diff --git a/lib/private/DB/QueryBuilder/ExpressionBuilder/ExpressionBuilder.php b/lib/private/DB/QueryBuilder/ExpressionBuilder/ExpressionBuilder.php
index 61eea80640e..d4c1a9db881 100644
--- a/lib/private/DB/QueryBuilder/ExpressionBuilder/ExpressionBuilder.php
+++ b/lib/private/DB/QueryBuilder/ExpressionBuilder/ExpressionBuilder.php
@@ -27,6 +27,7 @@
 namespace OC\DB\QueryBuilder\ExpressionBuilder;
 
 use Doctrine\DBAL\Query\Expression\ExpressionBuilder as DoctrineExpressionBuilder;
+use OC\DB\ConnectionAdapter;
 use OC\DB\QueryBuilder\CompositeExpression;
 use OC\DB\QueryBuilder\FunctionBuilder\FunctionBuilder;
 use OC\DB\QueryBuilder\Literal;
@@ -55,13 +56,13 @@ class ExpressionBuilder implements IExpressionBuilder {
 	/**
 	 * Initializes a new <tt>ExpressionBuilder</tt>.
 	 *
-	 * @param IDBConnection $connection
+	 * @param ConnectionAdapter $connection
 	 * @param IQueryBuilder $queryBuilder
 	 */
-	public function __construct(IDBConnection $connection, IQueryBuilder $queryBuilder) {
+	public function __construct(ConnectionAdapter $connection, IQueryBuilder $queryBuilder) {
 		$this->connection = $connection;
 		$this->helper = new QuoteHelper();
-		$this->expressionBuilder = new DoctrineExpressionBuilder($connection);
+		$this->expressionBuilder = new DoctrineExpressionBuilder($connection->getInner());
 		$this->functionBuilder = $queryBuilder->func();
 	}
 
diff --git a/lib/private/DB/QueryBuilder/ExpressionBuilder/MySqlExpressionBuilder.php b/lib/private/DB/QueryBuilder/ExpressionBuilder/MySqlExpressionBuilder.php
index 899f9277439..3e4119bb11c 100644
--- a/lib/private/DB/QueryBuilder/ExpressionBuilder/MySqlExpressionBuilder.php
+++ b/lib/private/DB/QueryBuilder/ExpressionBuilder/MySqlExpressionBuilder.php
@@ -24,9 +24,8 @@
 
 namespace OC\DB\QueryBuilder\ExpressionBuilder;
 
-use OC\DB\Connection;
+use OC\DB\ConnectionAdapter;
 use OCP\DB\QueryBuilder\IQueryBuilder;
-use OCP\IDBConnection;
 
 class MySqlExpressionBuilder extends ExpressionBuilder {
 
@@ -34,13 +33,13 @@ class MySqlExpressionBuilder extends ExpressionBuilder {
 	protected $charset;
 
 	/**
-	 * @param \OCP\IDBConnection|Connection $connection
+	 * @param ConnectionAdapter $connection
 	 * @param IQueryBuilder $queryBuilder
 	 */
-	public function __construct(IDBConnection $connection, IQueryBuilder $queryBuilder) {
+	public function __construct(ConnectionAdapter $connection, IQueryBuilder $queryBuilder) {
 		parent::__construct($connection, $queryBuilder);
 
-		$params = $connection->getParams();
+		$params = $connection->getInner()->getParams();
 		$this->charset = isset($params['charset']) ? $params['charset'] : 'utf8';
 	}
 
diff --git a/lib/private/DB/QueryBuilder/QueryBuilder.php b/lib/private/DB/QueryBuilder/QueryBuilder.php
index 2d5fe6ce575..657e52e54bc 100644
--- a/lib/private/DB/QueryBuilder/QueryBuilder.php
+++ b/lib/private/DB/QueryBuilder/QueryBuilder.php
@@ -30,11 +30,12 @@
 
 namespace OC\DB\QueryBuilder;
 
-use Doctrine\DBAL\Platforms\MySqlPlatform;
-use Doctrine\DBAL\Platforms\PostgreSqlPlatform;
+use Doctrine\DBAL\Platforms\MySQLPlatform;
+use Doctrine\DBAL\Platforms\OraclePlatform;
+use Doctrine\DBAL\Platforms\PostgreSQL94Platform;
 use Doctrine\DBAL\Platforms\SqlitePlatform;
 use Doctrine\DBAL\Query\QueryException;
-use OC\DB\OracleConnection;
+use OC\DB\ConnectionAdapter;
 use OC\DB\QueryBuilder\ExpressionBuilder\ExpressionBuilder;
 use OC\DB\QueryBuilder\ExpressionBuilder\MySqlExpressionBuilder;
 use OC\DB\QueryBuilder\ExpressionBuilder\OCIExpressionBuilder;
@@ -44,17 +45,18 @@ use OC\DB\QueryBuilder\FunctionBuilder\FunctionBuilder;
 use OC\DB\QueryBuilder\FunctionBuilder\OCIFunctionBuilder;
 use OC\DB\QueryBuilder\FunctionBuilder\PgSqlFunctionBuilder;
 use OC\DB\QueryBuilder\FunctionBuilder\SqliteFunctionBuilder;
+use OC\DB\ResultAdapter;
 use OC\SystemConfig;
+use OCP\DB\IResult;
 use OCP\DB\QueryBuilder\ILiteral;
 use OCP\DB\QueryBuilder\IParameter;
 use OCP\DB\QueryBuilder\IQueryBuilder;
 use OCP\DB\QueryBuilder\IQueryFunction;
-use OCP\IDBConnection;
 use OCP\ILogger;
 
 class QueryBuilder implements IQueryBuilder {
 
-	/** @var \OCP\IDBConnection */
+	/** @var ConnectionAdapter */
 	private $connection;
 
 	/** @var SystemConfig */
@@ -78,15 +80,15 @@ class QueryBuilder implements IQueryBuilder {
 	/**
 	 * Initializes a new QueryBuilder.
 	 *
-	 * @param IDBConnection $connection
+	 * @param ConnectionAdapter $connection
 	 * @param SystemConfig $systemConfig
 	 * @param ILogger $logger
 	 */
-	public function __construct(IDBConnection $connection, SystemConfig $systemConfig, ILogger $logger) {
+	public function __construct(ConnectionAdapter $connection, SystemConfig $systemConfig, ILogger $logger) {
 		$this->connection = $connection;
 		$this->systemConfig = $systemConfig;
 		$this->logger = $logger;
-		$this->queryBuilder = new \Doctrine\DBAL\Query\QueryBuilder($this->connection);
+		$this->queryBuilder = new \Doctrine\DBAL\Query\QueryBuilder($this->connection->getInner());
 		$this->helper = new QuoteHelper();
 	}
 
@@ -118,17 +120,20 @@ class QueryBuilder implements IQueryBuilder {
 	 * @return \OCP\DB\QueryBuilder\IExpressionBuilder
 	 */
 	public function expr() {
-		if ($this->connection instanceof OracleConnection) {
+		if ($this->connection->getDatabasePlatform() instanceof OraclePlatform) {
 			return new OCIExpressionBuilder($this->connection, $this);
-		} elseif ($this->connection->getDatabasePlatform() instanceof PostgreSqlPlatform) {
+		}
+		if ($this->connection->getDatabasePlatform() instanceof PostgreSQL94Platform) {
 			return new PgSqlExpressionBuilder($this->connection, $this);
-		} elseif ($this->connection->getDatabasePlatform() instanceof MySqlPlatform) {
+		}
+		if ($this->connection->getDatabasePlatform() instanceof MySQLPlatform) {
 			return new MySqlExpressionBuilder($this->connection, $this);
-		} elseif ($this->connection->getDatabasePlatform() instanceof SqlitePlatform) {
+		}
+		if ($this->connection->getDatabasePlatform() instanceof SqlitePlatform) {
 			return new SqliteExpressionBuilder($this->connection, $this);
-		} else {
-			return new ExpressionBuilder($this->connection, $this);
 		}
+
+		return new ExpressionBuilder($this->connection, $this);
 	}
 
 	/**
@@ -148,15 +153,17 @@ class QueryBuilder implements IQueryBuilder {
 	 * @return \OCP\DB\QueryBuilder\IFunctionBuilder
 	 */
 	public function func() {
-		if ($this->connection instanceof OracleConnection) {
+		if ($this->connection->getDatabasePlatform() instanceof OraclePlatform) {
 			return new OCIFunctionBuilder($this->helper);
-		} elseif ($this->connection->getDatabasePlatform() instanceof SqlitePlatform) {
+		}
+		if ($this->connection->getDatabasePlatform() instanceof SqlitePlatform) {
 			return new SqliteFunctionBuilder($this->helper);
-		} elseif ($this->connection->getDatabasePlatform() instanceof PostgreSqlPlatform) {
+		}
+		if ($this->connection->getDatabasePlatform() instanceof PostgreSQL94Platform) {
 			return new PgSqlFunctionBuilder($this->helper);
-		} else {
-			return new FunctionBuilder($this->helper);
 		}
+
+		return new FunctionBuilder($this->helper);
 	}
 
 	/**
@@ -192,7 +199,7 @@ class QueryBuilder implements IQueryBuilder {
 	 * Uses {@see Connection::executeQuery} for select statements and {@see Connection::executeUpdate}
 	 * for insert, update and delete statements.
 	 *
-	 * @return \Doctrine\DBAL\Driver\Statement|int
+	 * @return IResult|int
 	 */
 	public function execute() {
 		if ($this->systemConfig->getValue('log_query', false)) {
@@ -246,7 +253,11 @@ class QueryBuilder implements IQueryBuilder {
 			}
 		}
 
-		return $this->queryBuilder->execute();
+		$result = $this->queryBuilder->execute();
+		if (is_int($result)) {
+			return $result;
+		}
+		return new ResultAdapter($result);
 	}
 
 	/**
diff --git a/lib/private/DB/ReconnectWrapper.php b/lib/private/DB/ReconnectWrapper.php
index 9599d6b0fe6..a0170152862 100644
--- a/lib/private/DB/ReconnectWrapper.php
+++ b/lib/private/DB/ReconnectWrapper.php
@@ -44,12 +44,12 @@ class ReconnectWrapper extends \Doctrine\DBAL\Connection {
 
 		if ($this->lastConnectionCheck > $checkTime || $this->isTransactionActive()) {
 			return parent::connect();
-		} else {
-			$this->lastConnectionCheck = $now;
-			if (!$this->ping()) {
-				$this->close();
-			}
-			return parent::connect();
 		}
+
+		$this->lastConnectionCheck = $now;
+		if (!$this->isConnected()) {
+			$this->close();
+		}
+		return parent::connect();
 	}
 }
diff --git a/lib/private/DB/ResultAdapter.php b/lib/private/DB/ResultAdapter.php
new file mode 100644
index 00000000000..176de5b45ea
--- /dev/null
+++ b/lib/private/DB/ResultAdapter.php
@@ -0,0 +1,71 @@
+<?php
+/*
+ * @copyright 2021 Christoph Wurst <christoph@winzerhof-wurst.at>
+ *
+ * @author 2021 Christoph Wurst <christoph@winzerhof-wurst.at>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace OC\DB;
+
+use Doctrine\DBAL\Result;
+use OCP\DB\IResult;
+use PDO;
+
+/**
+ * Adapts DBAL 2.6 API for DBAL 3.x for backwards compatibility of a leaked type
+ */
+class ResultAdapter implements IResult {
+
+	/** @var Result */
+	private $inner;
+
+	public function __construct(Result $inner) {
+		$this->inner = $inner;
+	}
+
+	public function closeCursor(): bool {
+		$this->inner->free();
+
+		return true;
+	}
+
+	public function fetch(int $fetchMode = PDO::FETCH_ASSOC) {
+		return $this->inner->fetch($fetchMode);
+	}
+
+	public function fetchAll(int $fetchMode = PDO::FETCH_ASSOC): array {
+		if ($fetchMode !== PDO::FETCH_ASSOC && $fetchMode !== PDO::FETCH_NUM && $fetchMode !== PDO::FETCH_COLUMN) {
+			throw new \Exception('Fetch mode needs to be assoc, num or column.');
+		}
+		return $this->inner->fetchAll($fetchMode);
+	}
+
+	public function fetchColumn($columnIndex = 0) {
+		return $this->inner->fetchOne();
+	}
+
+	public function fetchOne() {
+		return $this->inner->fetchOne();
+	}
+
+	public function rowCount(): int {
+		return $this->inner->rowCount();
+	}
+}
diff --git a/lib/private/DB/SQLiteMigrator.php b/lib/private/DB/SQLiteMigrator.php
index 16f18be135e..24b6c02b31c 100644
--- a/lib/private/DB/SQLiteMigrator.php
+++ b/lib/private/DB/SQLiteMigrator.php
@@ -26,7 +26,6 @@
 
 namespace OC\DB;
 
-use Doctrine\DBAL\DBALException;
 use Doctrine\DBAL\Schema\Schema;
 use Doctrine\DBAL\Types\BigIntType;
 use Doctrine\DBAL\Types\Type;
@@ -34,42 +33,6 @@ use Doctrine\DBAL\Types\Type;
 class SQLiteMigrator extends Migrator {
 
 	/**
-	 * @param \Doctrine\DBAL\Schema\Schema $targetSchema
-	 * @throws \OC\DB\MigrationException
-	 *
-	 * For sqlite we simple make a copy of the entire database, and test the migration on that
-	 */
-	public function checkMigrate(\Doctrine\DBAL\Schema\Schema $targetSchema) {
-		$dbFile = $this->connection->getDatabase();
-		$tmpFile = $this->buildTempDatabase();
-		copy($dbFile, $tmpFile);
-
-		$connectionParams = [
-			'path' => $tmpFile,
-			'driver' => 'pdo_sqlite',
-		];
-		$conn = \Doctrine\DBAL\DriverManager::getConnection($connectionParams);
-		try {
-			$this->applySchema($targetSchema, $conn);
-			$conn->close();
-			unlink($tmpFile);
-		} catch (DBALException $e) {
-			$conn->close();
-			unlink($tmpFile);
-			throw new MigrationException('', $e->getMessage());
-		}
-	}
-
-	/**
-	 * @return string
-	 */
-	private function buildTempDatabase() {
-		$dataDir = $this->config->getSystemValue("datadirectory", \OC::$SERVERROOT . '/data');
-		$tmpFile = uniqid("oc_");
-		return "$dataDir/$tmpFile.db";
-	}
-
-	/**
 	 * @param Schema $targetSchema
 	 * @param \Doctrine\DBAL\Connection $connection
 	 * @return \Doctrine\DBAL\Schema\SchemaDiff
diff --git a/lib/private/DB/SQLiteSessionInit.php b/lib/private/DB/SQLiteSessionInit.php
index 0c53a0587f0..924a3b2758c 100644
--- a/lib/private/DB/SQLiteSessionInit.php
+++ b/lib/private/DB/SQLiteSessionInit.php
@@ -60,8 +60,9 @@ class SQLiteSessionInit implements EventSubscriber {
 		$sensitive = $this->caseSensitiveLike ? 'true' : 'false';
 		$args->getConnection()->executeUpdate('PRAGMA case_sensitive_like = ' . $sensitive);
 		$args->getConnection()->executeUpdate('PRAGMA journal_mode = ' . $this->journalMode);
-		/** @var \PDO $pdo */
-		$pdo = $args->getConnection()->getWrappedConnection();
+		/** @var \Doctrine\DBAL\Driver\PDO\Connection $connection */
+		$connection = $args->getConnection()->getWrappedConnection();
+		$pdo = $connection->getWrappedConnection();
 		$pdo->sqliteCreateFunction('md5', 'md5', 1);
 	}
 
diff --git a/lib/private/DB/SchemaWrapper.php b/lib/private/DB/SchemaWrapper.php
index 440008d35b3..20ae5b6faa6 100644
--- a/lib/private/DB/SchemaWrapper.php
+++ b/lib/private/DB/SchemaWrapper.php
@@ -26,11 +26,10 @@ namespace OC\DB;
 
 use Doctrine\DBAL\Schema\Schema;
 use OCP\DB\ISchemaWrapper;
-use OCP\IDBConnection;
 
 class SchemaWrapper implements ISchemaWrapper {
 
-	/** @var IDBConnection|Connection */
+	/** @var Connection */
 	protected $connection;
 
 	/** @var Schema */
@@ -39,10 +38,7 @@ class SchemaWrapper implements ISchemaWrapper {
 	/** @var array */
 	protected $tablesToDelete = [];
 
-	/**
-	 * @param IDBConnection $connection
-	 */
-	public function __construct(IDBConnection $connection) {
+	public function __construct(Connection $connection) {
 		$this->connection = $connection;
 		$this->schema = $this->connection->createSchema();
 	}
diff --git a/lib/private/Files/Cache/Cache.php b/lib/private/Files/Cache/Cache.php
index dbe0dd9d778..2513abd525f 100644
--- a/lib/private/Files/Cache/Cache.php
+++ b/lib/private/Files/Cache/Cache.php
@@ -39,8 +39,8 @@
 
 namespace OC\Files\Cache;
 
-use Doctrine\DBAL\Driver\Statement;
 use Doctrine\DBAL\Exception\UniqueConstraintViolationException;
+use OCP\DB\IResult;
 use OCP\DB\QueryBuilder\IQueryBuilder;
 use OCP\EventDispatcher\IEventDispatcher;
 use OCP\Files\Cache\CacheEntryInsertedEvent;
@@ -486,7 +486,7 @@ class Cache implements ICache {
 			->wherePath($file);
 
 		$result = $query->execute();
-		$id = $result->fetchColumn();
+		$id = $result->fetchOne();
 		$result->closeCursor();
 
 		return $id === false ? -1 : (int)$id;
@@ -746,7 +746,7 @@ class Cache implements ICache {
 			->wherePath($file);
 
 		$result = $query->execute();
-		$size = $result->fetchColumn();
+		$size = $result->fetchOne();
 		$result->closeCursor();
 
 		if ($size !== false) {
@@ -793,10 +793,10 @@ class Cache implements ICache {
 	}
 
 	/**
-	 * @param Statement $result
+	 * @param IResult $result
 	 * @return CacheEntry[]
 	 */
-	private function searchResultToCacheEntries(Statement $result) {
+	private function searchResultToCacheEntries(IResult $result): array {
 		$files = $result->fetchAll();
 
 		return array_map(function (array $data) {
@@ -870,7 +870,9 @@ class Cache implements ICache {
 		}
 
 		$result = $query->execute();
-		return $this->searchResultToCacheEntries($result);
+		$cacheEntries = $this->searchResultToCacheEntries($result);
+		$result->closeCursor();
+		return $cacheEntries;
 	}
 
 	/**
@@ -912,7 +914,7 @@ class Cache implements ICache {
 				->andWhere($query->expr()->lt('size', $query->createNamedParameter(0, IQueryBuilder::PARAM_INT)));
 
 			$result = $query->execute();
-			$size = (int)$result->fetchColumn();
+			$size = (int)$result->fetchOne();
 			$result->closeCursor();
 
 			return $size;
@@ -1002,7 +1004,7 @@ class Cache implements ICache {
 			->setMaxResults(1);
 
 		$result = $query->execute();
-		$path = $result->fetchColumn();
+		$path = $result->fetchOne();
 		$result->closeCursor();
 
 		return $path;
@@ -1022,7 +1024,7 @@ class Cache implements ICache {
 			->whereFileId($id);
 
 		$result = $query->execute();
-		$path = $result->fetchColumn();
+		$path = $result->fetchOne();
 		$result->closeCursor();
 
 		if ($path === false) {
diff --git a/lib/private/Files/Cache/Scanner.php b/lib/private/Files/Cache/Scanner.php
index 26264321a9a..0dbc34fae2f 100644
--- a/lib/private/Files/Cache/Scanner.php
+++ b/lib/private/Files/Cache/Scanner.php
@@ -36,6 +36,7 @@
 
 namespace OC\Files\Cache;
 
+use Doctrine\DBAL\Exception;
 use OC\Files\Filesystem;
 use OC\Hooks\BasicEmitter;
 use OCP\Files\Cache\IScanner;
@@ -437,7 +438,7 @@ class Scanner extends BasicEmitter implements IScanner {
 						$size += $data['size'];
 					}
 				}
-			} catch (\Doctrine\DBAL\DBALException $ex) {
+			} catch (Exception $ex) {
 				// might happen if inserting duplicate while a scanning
 				// process is running in parallel
 				// log and ignore
diff --git a/lib/private/Group/Database.php b/lib/private/Group/Database.php
index 97094c67728..c49f3bce596 100644
--- a/lib/private/Group/Database.php
+++ b/lib/private/Group/Database.php
@@ -410,7 +410,7 @@ class Database extends ABackend implements
 		}
 
 		$result = $query->execute();
-		$count = $result->fetchColumn();
+		$count = $result->fetchOne();
 		$result->closeCursor();
 
 		if ($count !== false) {
@@ -442,7 +442,7 @@ class Database extends ABackend implements
 			->andWhere($query->expr()->eq('gid', $query->createNamedParameter($gid), IQueryBuilder::PARAM_STR));
 
 		$result = $query->execute();
-		$count = $result->fetchColumn();
+		$count = $result->fetchOne();
 		$result->closeCursor();
 
 		if ($count !== false) {
@@ -467,7 +467,7 @@ class Database extends ABackend implements
 			->where($query->expr()->eq('gid', $query->createNamedParameter($gid)));
 
 		$result = $query->execute();
-		$displayName = $result->fetchColumn();
+		$displayName = $result->fetchOne();
 		$result->closeCursor();
 
 		return (string) $displayName;
diff --git a/lib/private/Installer.php b/lib/private/Installer.php
index 0b020aed569..e0eb8e9de18 100644
--- a/lib/private/Installer.php
+++ b/lib/private/Installer.php
@@ -45,6 +45,7 @@ use OC\App\AppStore\Bundles\Bundle;
 use OC\App\AppStore\Fetcher\AppFetcher;
 use OC\AppFramework\Bootstrap\Coordinator;
 use OC\Archive\TAR;
+use OC\DB\Connection;
 use OC_App;
 use OC_DB;
 use OC_Helper;
@@ -158,7 +159,7 @@ class Installer {
 				OC_DB::updateDbFromStructure($basedir.'/appinfo/database.xml');
 			}
 		} else {
-			$ms = new \OC\DB\MigrationService($info['id'], \OC::$server->getDatabaseConnection());
+			$ms = new \OC\DB\MigrationService($info['id'], \OC::$server->get(Connection::class));
 			$ms->migrate('latest', true);
 		}
 		if ($previousVersion) {
@@ -593,7 +594,7 @@ class Installer {
 				);
 			}
 		} else {
-			$ms = new \OC\DB\MigrationService($app, \OC::$server->getDatabaseConnection());
+			$ms = new \OC\DB\MigrationService($app, \OC::$server->get(Connection::class));
 			$ms->migrate('latest', true);
 		}
 
diff --git a/lib/private/Lock/DBLockingProvider.php b/lib/private/Lock/DBLockingProvider.php
index c6b9cf63780..30566c7b253 100644
--- a/lib/private/Lock/DBLockingProvider.php
+++ b/lib/private/Lock/DBLockingProvider.php
@@ -159,7 +159,7 @@ class DBLockingProvider extends AbstractLockingProvider {
 		}
 		$query = $this->connection->prepare('SELECT `lock` from `*PREFIX*file_locks` WHERE `key` = ?');
 		$query->execute([$path]);
-		$lockValue = (int)$query->fetchColumn();
+		$lockValue = (int)$query->fetchOne();
 		if ($type === self::LOCK_SHARED) {
 			if ($this->isLocallyLocked($path)) {
 				// if we have a shared lock we kept open locally but it's released we always have at least 1 shared lock in the db
diff --git a/lib/private/Repair.php b/lib/private/Repair.php
index 80a8a8a87c1..e4f75b43fdc 100644
--- a/lib/private/Repair.php
+++ b/lib/private/Repair.php
@@ -36,6 +36,8 @@ namespace OC;
 
 use OC\App\AppStore\Bundles\BundleFetcher;
 use OC\Avatar\AvatarManager;
+use OC\DB\Connection;
+use OC\DB\ConnectionAdapter;
 use OC\Repair\AddBruteForceCleanupJob;
 use OC\Repair\AddCleanupUpdaterBackupsJob;
 use OC\Repair\CleanTags;
@@ -210,13 +212,16 @@ class Repair implements IOutput {
 	 * @return IRepairStep[]
 	 */
 	public static function getBeforeUpgradeRepairSteps() {
-		$connection = \OC::$server->getDatabaseConnection();
+		/** @var Connection $connection */
+		$connection = \OC::$server->get(Connection::class);
+		/** @var ConnectionAdapter $connectionAdapter */
+		$connectionAdapter = \OC::$server->get(ConnectionAdapter::class);
 		$config = \OC::$server->getConfig();
 		$steps = [
-			new Collation(\OC::$server->getConfig(), \OC::$server->getLogger(), $connection, true),
+			new Collation(\OC::$server->getConfig(), \OC::$server->getLogger(), $connectionAdapter, true),
 			new SqliteAutoincrement($connection),
-			new SaveAccountsTableData($connection, $config),
-			new DropAccountTermsTable($connection)
+			new SaveAccountsTableData($connectionAdapter, $config),
+			new DropAccountTermsTable($connectionAdapter)
 		];
 
 		return $steps;
diff --git a/lib/private/Repair/Collation.php b/lib/private/Repair/Collation.php
index fb0e0192693..d2974c1680a 100644
--- a/lib/private/Repair/Collation.php
+++ b/lib/private/Repair/Collation.php
@@ -28,7 +28,7 @@
 namespace OC\Repair;
 
 use Doctrine\DBAL\Exception\DriverException;
-use Doctrine\DBAL\Platforms\MySqlPlatform;
+use Doctrine\DBAL\Platforms\MySQLPlatform;
 use OCP\IConfig;
 use OCP\IDBConnection;
 use OCP\ILogger;
@@ -69,7 +69,7 @@ class Collation implements IRepairStep {
 	 * Fix mime types
 	 */
 	public function run(IOutput $output) {
-		if (!$this->connection->getDatabasePlatform() instanceof MySqlPlatform) {
+		if (!$this->connection->getDatabasePlatform() instanceof MySQLPlatform) {
 			$output->info('Not a mysql database -> nothing to do');
 			return;
 		}
diff --git a/lib/private/Repair/RemoveLinkShares.php b/lib/private/Repair/RemoveLinkShares.php
index 3a0dd6f2884..32cbd1f73f8 100644
--- a/lib/private/Repair/RemoveLinkShares.php
+++ b/lib/private/Repair/RemoveLinkShares.php
@@ -30,8 +30,8 @@ declare(strict_types=1);
 
 namespace OC\Repair;
 
-use Doctrine\DBAL\Driver\Statement;
 use OCP\AppFramework\Utility\ITimeFactory;
+use OCP\DB\IResult;
 use OCP\DB\QueryBuilder\IQueryBuilder;
 use OCP\IConfig;
 use OCP\IDBConnection;
@@ -138,10 +138,8 @@ class RemoveLinkShares implements IRepairStep {
 
 	/**
 	 * Get the cursor to fetch all the shares
-	 *
-	 * @return \Doctrine\DBAL\Driver\Statement
 	 */
-	private function getShares(): Statement {
+	private function getShares(): IResult {
 		$subQuery = $this->connection->getQueryBuilder();
 		$subQuery->select('*')
 			->from('share')
@@ -160,7 +158,9 @@ class RemoveLinkShares implements IRepairStep {
 				$query->expr()->eq('s2.share_type', $query->expr()->literal(2, IQueryBuilder::PARAM_INT))
 			))
 			->andWhere($query->expr()->eq('s1.item_source', 's2.item_source'));
-		return $query->execute();
+		/** @var IResult $result */
+		$result = $query->execute();
+		return $result;
 	}
 
 	/**
@@ -210,13 +210,13 @@ class RemoveLinkShares implements IRepairStep {
 	private function repair(IOutput $output, int $total): void {
 		$output->startProgress($total);
 
-		$shareCursor = $this->getShares();
-		while ($data = $shareCursor->fetch()) {
+		$shareResult = $this->getShares();
+		while ($data = $shareResult->fetch()) {
 			$this->processShare($data);
 			$output->advance();
 		}
 		$output->finishProgress();
-		$shareCursor->closeCursor();
+		$shareResult->closeCursor();
 
 		// Notifiy all admins
 		$adminGroup = $this->groupManager->get('admin');
diff --git a/lib/private/Repair/RepairMimeTypes.php b/lib/private/Repair/RepairMimeTypes.php
index 3e6fa51b196..d0e3bbff707 100644
--- a/lib/private/Repair/RepairMimeTypes.php
+++ b/lib/private/Repair/RepairMimeTypes.php
@@ -71,7 +71,7 @@ class RepairMimeTypes implements IRepairStep {
 		if (empty($this->folderMimeTypeId)) {
 			$query->setParameter('mimetype', 'httpd/unix-directory');
 			$result = $query->execute();
-			$this->folderMimeTypeId = (int)$result->fetchColumn();
+			$this->folderMimeTypeId = (int)$result->fetchOne();
 			$result->closeCursor();
 		}
 
@@ -88,7 +88,7 @@ class RepairMimeTypes implements IRepairStep {
 			// get target mimetype id
 			$query->setParameter('mimetype', $mimetype);
 			$result = $query->execute();
-			$mimetypeId = (int)$result->fetchColumn();
+			$mimetypeId = (int)$result->fetchOne();
 			$result->closeCursor();
 
 			if (!$mimetypeId) {
@@ -242,7 +242,7 @@ class RepairMimeTypes implements IRepairStep {
 		if (version_compare($ocVersionFromBeforeUpdate, '20.0.0.5', '<') && $this->introduceOpenDocumentTemplates()) {
 			$out->info('Fixed OpenDocument template mime types');
 		}
-		
+
 		if (version_compare($ocVersionFromBeforeUpdate, '21.0.0.7', '<') && $this->introduceOrgModeType()) {
 			$out->info('Fixed orgmode mime types');
 		}
diff --git a/lib/private/Server.php b/lib/private/Server.php
index 687eba68e73..680eea3beca 100644
--- a/lib/private/Server.php
+++ b/lib/private/Server.php
@@ -77,6 +77,8 @@ use OC\Comments\ManagerFactory as CommentsManagerFactory;
 use OC\Contacts\ContactsMenu\ActionFactory;
 use OC\Contacts\ContactsMenu\ContactsStore;
 use OC\Dashboard\DashboardManager;
+use OC\DB\Connection;
+use OC\DB\ConnectionAdapter;
 use OC\Diagnostics\EventLogger;
 use OC\Diagnostics\QueryLogger;
 use OC\EventDispatcher\SymfonyAdapter;
@@ -792,7 +794,8 @@ class Server extends ServerContainer implements IServerContainer {
 		/** @deprecated 19.0.0 */
 		$this->registerDeprecatedAlias('CredentialsManager', ICredentialsManager::class);
 
-		$this->registerService(IDBConnection::class, function (Server $c) {
+		$this->registerAlias(IDBConnection::class, ConnectionAdapter::class);
+		$this->registerService(Connection::class, function (Server $c) {
 			$systemConfig = $c->get(SystemConfig::class);
 			$factory = new \OC\DB\ConnectionFactory($systemConfig);
 			$type = $systemConfig->getValue('dbtype', 'sqlite');
diff --git a/lib/private/Setup/AbstractDatabase.php b/lib/private/Setup/AbstractDatabase.php
index 8a9aed09f1b..e0761db3070 100644
--- a/lib/private/Setup/AbstractDatabase.php
+++ b/lib/private/Setup/AbstractDatabase.php
@@ -29,6 +29,7 @@
 
 namespace OC\Setup;
 
+use OC\DB\Connection;
 use OC\DB\ConnectionFactory;
 use OC\DB\MigrationService;
 use OC\SystemConfig;
@@ -108,7 +109,7 @@ abstract class AbstractDatabase {
 	 * @param array $configOverwrite
 	 * @return \OC\DB\Connection
 	 */
-	protected function connect(array $configOverwrite = []) {
+	protected function connect(array $configOverwrite = []): Connection {
 		$connectionParams = [
 			'host' => $this->dbHost,
 			'user' => $this->dbUser,
@@ -149,7 +150,7 @@ abstract class AbstractDatabase {
 		if (!is_dir(\OC::$SERVERROOT."/core/Migrations")) {
 			return;
 		}
-		$ms = new MigrationService('core', \OC::$server->getDatabaseConnection());
+		$ms = new MigrationService('core', \OC::$server->get(Connection::class));
 		$ms->migrate('latest', true);
 	}
 }
diff --git a/lib/private/Setup/MySQL.php b/lib/private/Setup/MySQL.php
index 966c97edf55..21339dc46d0 100644
--- a/lib/private/Setup/MySQL.php
+++ b/lib/private/Setup/MySQL.php
@@ -31,6 +31,7 @@
 
 namespace OC\Setup;
 
+use OC\DB\ConnectionAdapter;
 use OC\DB\MySqlTools;
 use OCP\IDBConnection;
 use OCP\ILogger;
@@ -45,12 +46,12 @@ class MySQL extends AbstractDatabase {
 
 		// detect mb4
 		$tools = new MySqlTools();
-		if ($tools->supports4ByteCharset($connection)) {
+		if ($tools->supports4ByteCharset(new ConnectionAdapter($connection))) {
 			$this->config->setValue('mysql.utf8mb4', true);
 			$connection = $this->connect(['dbname' => null]);
 		}
 
-		$this->createSpecificUser($username, $connection);
+		$this->createSpecificUser($username, new ConnectionAdapter($connection));
 
 		//create the database
 		$this->createDatabase($connection);
@@ -156,27 +157,24 @@ class MySQL extends AbstractDatabase {
 					$result = $connection->executeQuery($query, [$adminUser]);
 
 					//current dbuser has admin rights
-					if ($result) {
-						$data = $result->fetchAll();
-						//new dbuser does not exist
-						if (count($data) === 0) {
-							//use the admin login data for the new database user
-							$this->dbUser = $adminUser;
-
-							//create a random password so we don't need to store the admin password in the config file
-							$this->dbPassword = $this->random->generate(30);
-
-							$this->createDBUser($connection);
-
-							break;
-						} else {
-							//repeat with different username
-							$length = strlen((string)$i);
-							$adminUser = substr('oc_' . $username, 0, 16 - $length) . $i;
-							$i++;
-						}
-					} else {
+					$data = $result->fetchAll();
+					$result->closeCursor();
+					//new dbuser does not exist
+					if (count($data) === 0) {
+						//use the admin login data for the new database user
+						$this->dbUser = $adminUser;
+
+						//create a random password so we don't need to store the admin password in the config file
+						$this->dbPassword = $this->random->generate(30);
+
+						$this->createDBUser($connection);
+
 						break;
+					} else {
+						//repeat with different username
+						$length = strlen((string)$i);
+						$adminUser = substr('oc_' . $username, 0, 16 - $length) . $i;
+						$i++;
 					}
 				}
 			}
diff --git a/lib/private/Setup/PostgreSQL.php b/lib/private/Setup/PostgreSQL.php
index 1f0b7b8f894..7e59bf297f1 100644
--- a/lib/private/Setup/PostgreSQL.php
+++ b/lib/private/Setup/PostgreSQL.php
@@ -30,8 +30,8 @@
 namespace OC\Setup;
 
 use OC\DatabaseException;
+use OC\DB\Connection;
 use OC\DB\QueryBuilder\Literal;
-use OCP\IDBConnection;
 
 class PostgreSQL extends AbstractDatabase {
 	public $dbprettyname = 'PostgreSQL';
@@ -103,7 +103,7 @@ class PostgreSQL extends AbstractDatabase {
 		}
 	}
 
-	private function createDatabase(IDBConnection $connection) {
+	private function createDatabase(Connection $connection) {
 		if (!$this->databaseExists($connection)) {
 			//The database does not exists... let's create it
 			$query = $connection->prepare("CREATE DATABASE " . addslashes($this->dbName) . " OWNER " . addslashes($this->dbUser));
@@ -124,7 +124,7 @@ class PostgreSQL extends AbstractDatabase {
 		}
 	}
 
-	private function userExists(IDBConnection $connection) {
+	private function userExists(Connection $connection) {
 		$builder = $connection->getQueryBuilder();
 		$builder->automaticTablePrefix(false);
 		$query = $builder->select('*')
@@ -134,7 +134,7 @@ class PostgreSQL extends AbstractDatabase {
 		return $result->rowCount() > 0;
 	}
 
-	private function databaseExists(IDBConnection $connection) {
+	private function databaseExists(Connection $connection) {
 		$builder = $connection->getQueryBuilder();
 		$builder->automaticTablePrefix(false);
 		$query = $builder->select('datname')
@@ -144,7 +144,7 @@ class PostgreSQL extends AbstractDatabase {
 		return $result->rowCount() > 0;
 	}
 
-	private function createDBUser(IDBConnection $connection) {
+	private function createDBUser(Connection $connection) {
 		$dbUser = $this->dbUser;
 		try {
 			$i = 1;
diff --git a/lib/private/Tags.php b/lib/private/Tags.php
index 720e9dd5d7d..8e32f3925e3 100644
--- a/lib/private/Tags.php
+++ b/lib/private/Tags.php
@@ -230,10 +230,6 @@ class Tags implements ITags {
 					}
 					$entries[$objId][] = $row['category'];
 				}
-				if ($result === null) {
-					\OCP\Util::writeLog('core', __METHOD__. 'DB error: ' . \OC::$server->getDatabaseConnection()->getError(), ILogger::ERROR);
-					return false;
-				}
 			}
 		} catch (\Exception $e) {
 			\OC::$server->getLogger()->logException($e, [
diff --git a/lib/private/Updater.php b/lib/private/Updater.php
index ec0a50cc6ca..09aa955283c 100644
--- a/lib/private/Updater.php
+++ b/lib/private/Updater.php
@@ -37,6 +37,7 @@
 
 namespace OC;
 
+use OC\DB\Connection;
 use OC\DB\MigrationService;
 use OC\Hooks\BasicEmitter;
 use OC\IntegrityCheck\Checker;
@@ -298,7 +299,7 @@ class Updater extends BasicEmitter {
 		$this->emit('\OC\Updater', 'dbUpgradeBefore');
 
 		// execute core migrations
-		$ms = new MigrationService('core', \OC::$server->getDatabaseConnection());
+		$ms = new MigrationService('core', \OC::$server->get(Connection::class));
 		$ms->migrate();
 
 		$this->emit('\OC\Updater', 'dbUpgrade');
diff --git a/lib/private/User/Database.php b/lib/private/User/Database.php
index 7c936acd0bd..85e22d196e4 100644
--- a/lib/private/User/Database.php
+++ b/lib/private/User/Database.php
@@ -436,7 +436,7 @@ class Database extends ABackend implements
 			->from($this->table);
 		$result = $query->execute();
 
-		return $result->fetchColumn();
+		return $result->fetchOne();
 	}
 
 	/**
diff --git a/lib/private/User/Manager.php b/lib/private/User/Manager.php
index 8e441e2e419..e447b0bfcf2 100644
--- a/lib/private/User/Manager.php
+++ b/lib/private/User/Manager.php
@@ -505,7 +505,7 @@ class Manager extends PublicEmitter implements IUserManager {
 
 
 		$result = $queryBuilder->execute();
-		$count = $result->fetchColumn();
+		$count = $result->fetchOne();
 		$result->closeCursor();
 
 		if ($count !== false) {
@@ -535,7 +535,7 @@ class Manager extends PublicEmitter implements IUserManager {
 			->andWhere($queryBuilder->expr()->in('gid', $queryBuilder->createNamedParameter($groups, IQueryBuilder::PARAM_STR_ARRAY)));
 
 		$result = $queryBuilder->execute();
-		$count = $result->fetchColumn();
+		$count = $result->fetchOne();
 		$result->closeCursor();
 
 		if ($count !== false) {
@@ -563,7 +563,7 @@ class Manager extends PublicEmitter implements IUserManager {
 
 		$query = $queryBuilder->execute();
 
-		$result = (int)$query->fetchColumn();
+		$result = (int)$query->fetchOne();
 		$query->closeCursor();
 
 		return $result;
diff --git a/lib/private/legacy/OC_App.php b/lib/private/legacy/OC_App.php
index 32d2569d0a0..a64b13f1e2c 100644
--- a/lib/private/legacy/OC_App.php
+++ b/lib/private/legacy/OC_App.php
@@ -989,7 +989,7 @@ class OC_App {
 		if (file_exists($appPath . '/appinfo/database.xml')) {
 			OC_DB::updateDbFromStructure($appPath . '/appinfo/database.xml');
 		} else {
-			$ms = new MigrationService($appId, \OC::$server->getDatabaseConnection());
+			$ms = new MigrationService($appId, \OC::$server->get(\OC\DB\Connection::class));
 			$ms->migrate();
 		}
 
diff --git a/lib/private/legacy/OC_DB.php b/lib/private/legacy/OC_DB.php
index 11cd1f4cae0..b5b6c737046 100644
--- a/lib/private/legacy/OC_DB.php
+++ b/lib/private/legacy/OC_DB.php
@@ -44,7 +44,7 @@ class OC_DB {
 	 * @return \OC\DB\MDB2SchemaManager
 	 */
 	private static function getMDB2SchemaManager() {
-		return new \OC\DB\MDB2SchemaManager(\OC::$server->getDatabaseConnection());
+		return new \OC\DB\MDB2SchemaManager(\OC::$server->get(\OC\DB\Connection::class));
 	}
 
 	/**
@@ -70,7 +70,7 @@ class OC_DB {
 		// return the result
 		try {
 			$result = $connection->prepare($query, $limit, $offset);
-		} catch (\Doctrine\DBAL\DBALException $e) {
+		} catch (\Doctrine\DBAL\Exception $e) {
 			throw new \OC\DatabaseException($e->getMessage());
 		}
 		// differentiate between query and manipulation
@@ -160,18 +160,6 @@ class OC_DB {
 	}
 
 	/**
-	 * saves database schema to xml file
-	 * @param string $file name of file
-	 * @return bool
-	 *
-	 * TODO: write more documentation
-	 */
-	public static function getDbStructure($file) {
-		$schemaManager = self::getMDB2SchemaManager();
-		return $schemaManager->getDbStructure($file);
-	}
-
-	/**
 	 * Creates tables from XML file
 	 * @param string $file file to read structure from
 	 * @return bool
@@ -211,7 +199,7 @@ class OC_DB {
 	}
 
 	/**
-	 * check if a result is an error and throws an exception, works with \Doctrine\DBAL\DBALException
+	 * check if a result is an error and throws an exception, works with \Doctrine\DBAL\Exception
 	 * @param mixed $result
 	 * @param string $message
 	 * @return void
diff --git a/lib/private/legacy/OC_DB_StatementWrapper.php b/lib/private/legacy/OC_DB_StatementWrapper.php
index 667c2de9678..cc2320015a3 100644
--- a/lib/private/legacy/OC_DB_StatementWrapper.php
+++ b/lib/private/legacy/OC_DB_StatementWrapper.php
@@ -28,6 +28,8 @@
  *
  */
 
+use OCP\DB\IPreparedStatement;
+
 /**
  * small wrapper around \Doctrine\DBAL\Driver\Statement to make it behave, more like an MDB2 Statement
  *
@@ -38,17 +40,20 @@
  * @method array fetchAll(integer $fetchMode = null);
  */
 class OC_DB_StatementWrapper {
-	/**
-	 * @var \Doctrine\DBAL\Driver\Statement
-	 */
+	/** @var IPreparedStatement */
 	private $statement = null;
+
+	/** @var bool */
 	private $isManipulation = false;
+
+	/** @var array */
 	private $lastArguments = [];
 
 	/**
+	 * @param IPreparedStatement $statement
 	 * @param boolean $isManipulation
 	 */
-	public function __construct($statement, $isManipulation) {
+	public function __construct(IPreparedStatement $statement, $isManipulation) {
 		$this->statement = $statement;
 		$this->isManipulation = $isManipulation;
 	}
@@ -63,31 +68,34 @@ class OC_DB_StatementWrapper {
 	/**
 	 * make execute return the result instead of a bool
 	 *
-	 * @param array $input
+	 * @param mixed[] $input
 	 * @return \OC_DB_StatementWrapper|int|bool
+	 * @deprecated
 	 */
 	public function execute($input = []) {
 		$this->lastArguments = $input;
-		if (count($input) > 0) {
-			$result = $this->statement->execute($input);
-		} else {
-			$result = $this->statement->execute();
-		}
-
-		if ($result === false) {
+		try {
+			if (count($input) > 0) {
+				$result = $this->statement->execute($input);
+			} else {
+				$result = $this->statement->execute();
+			}
+		} catch (\Doctrine\DBAL\Exception $e) {
 			return false;
 		}
+
 		if ($this->isManipulation) {
 			return $this->statement->rowCount();
-		} else {
-			return $this;
 		}
+
+		return $this;
 	}
 
 	/**
 	 * provide an alias for fetch
 	 *
 	 * @return mixed
+	 * @deprecated
 	 */
 	public function fetchRow() {
 		return $this->statement->fetch();
@@ -97,11 +105,11 @@ class OC_DB_StatementWrapper {
 	 * Provide a simple fetchOne.
 	 *
 	 * fetch single column from the next row
-	 * @param int $column the column number to fetch
 	 * @return string
+	 * @deprecated
 	 */
-	public function fetchOne($column = 0) {
-		return $this->statement->fetchColumn($column);
+	public function fetchOne() {
+		return $this->statement->fetchOne();
 	}
 
 	/**
diff --git a/lib/private/legacy/OC_Util.php b/lib/private/legacy/OC_Util.php
index 4176dfbb229..d5805719ea2 100644
--- a/lib/private/legacy/OC_Util.php
+++ b/lib/private/legacy/OC_Util.php
@@ -993,7 +993,7 @@ class OC_Util {
 						];
 					}
 				}
-			} catch (\Doctrine\DBAL\DBALException $e) {
+			} catch (\Doctrine\DBAL\Exception $e) {
 				$logger = \OC::$server->getLogger();
 				$logger->warning('Error occurred while checking PostgreSQL version, assuming >= 9');
 				$logger->logException($e);
diff --git a/lib/public/DB/IPreparedStatement.php b/lib/public/DB/IPreparedStatement.php
new file mode 100644
index 00000000000..6b6617ba5ea
--- /dev/null
+++ b/lib/public/DB/IPreparedStatement.php
@@ -0,0 +1,127 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * @copyright 2021 Christoph Wurst <christoph@winzerhof-wurst.at>
+ *
+ * @author 2021 Christoph Wurst <christoph@winzerhof-wurst.at>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace OCP\DB;
+
+use Doctrine\DBAL\Exception;
+use Doctrine\DBAL\ParameterType;
+use PDO;
+
+/**
+ * @since 21.0.0
+ */
+interface IPreparedStatement {
+
+	/**
+	 * @return true
+	 *
+	 * @since 21.0.0
+	 * @deprecated 21.0.0 use \OCP\DB\IResult::closeCursor on the \OCP\DB\IResult returned by \OCP\IDBConnection::prepare
+	 */
+	public function closeCursor(): bool;
+
+	/**
+	 * @param int $fetchMode
+	 *
+	 * @return mixed
+	 *
+	 * @since 21.0.0
+	 * @deprecated 21.0.0 use \OCP\DB\IResult::fetch on the \OCP\DB\IResult returned by \OCP\IDBConnection::prepare
+	 */
+	public function fetch(int $fetchMode = PDO::FETCH_ASSOC);
+
+	/**
+	 * @param int $fetchMode
+	 *
+	 * @return mixed[]
+	 *
+	 * @since 21.0.0
+	 * @deprecated 21.0.0 use \OCP\DB\IResult::fetchAll on the \OCP\DB\IResult returned by \OCP\IDBConnection::prepare
+	 */
+	public function fetchAll(int $fetchMode = PDO::FETCH_ASSOC);
+
+	/**
+	 * @return mixed
+	 *
+	 * @since 21.0.0
+	 * @deprecated 21.0.0 use \OCP\DB\IResult::fetchColumn on the \OCP\DB\IResult returned by \OCP\IDBConnection::prepare
+	 */
+	public function fetchColumn();
+
+	/**
+	 * @return mixed
+	 *
+	 * @since 21.0.0
+	 * @deprecated 21.0.0 use \OCP\DB\IResult::fetchOne on the \OCP\DB\IResult returned by \OCP\IDBConnection::prepare
+	 */
+	public function fetchOne();
+
+	/**
+	 * @param int|string $param
+	 * @param mixed $value
+	 * @param int $type
+	 *
+	 * @return bool
+	 *
+	 * @throws Exception
+	 *
+	 * @since 21.0.0
+	 */
+	public function bindValue($param, $value, $type = ParameterType::STRING): bool;
+
+	/**
+	 * @param int|string $param
+	 * @param mixed $variable
+	 * @param int $type
+	 * @param int|null $length
+	 *
+	 * @return bool
+	 *
+	 * @throws Exception
+	 *
+	 * @since 21.0.0
+	 */
+	public function bindParam($param, &$variable, $type = ParameterType::STRING, $length = null): bool;
+
+	/**
+	 * @param mixed[]|null $params
+	 *
+	 * @return IResult
+	 *
+	 * @since 21.0.0
+	 * @throws Exception
+	 */
+	public function execute($params = null): IResult;
+
+	/**
+	 * @return int
+	 *
+	 * @since 21.0.0
+	 *
+	 * @throws Exception
+	 * @deprecated 21.0.0 use \OCP\DB\IResult::rowCount on the \OCP\DB\IResult returned by \OCP\IDBConnection::prepare
+	 */
+	public function rowCount(): int;
+}
diff --git a/lib/public/DB/IResult.php b/lib/public/DB/IResult.php
new file mode 100644
index 00000000000..10c788ebbf6
--- /dev/null
+++ b/lib/public/DB/IResult.php
@@ -0,0 +1,83 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * @copyright 2021 Christoph Wurst <christoph@winzerhof-wurst.at>
+ *
+ * @author 2021 Christoph Wurst <christoph@winzerhof-wurst.at>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace OCP\DB;
+
+use PDO;
+
+/**
+ * @since 21.0.0
+ */
+interface IResult {
+
+	/**
+	 * @return true
+	 *
+	 * @since 21.0.0
+	 */
+	public function closeCursor(): bool;
+
+	/**
+	 * @param int $fetchMode
+	 *
+	 * @return mixed
+	 *
+	 * @since 21.0.0
+	 */
+	public function fetch(int $fetchMode = PDO::FETCH_ASSOC);
+
+	/**
+	 * @param int $fetchMode (one of PDO::FETCH_ASSOC, PDO::FETCH_NUM or PDO::FETCH_COLUMN (2, 3 or 7)
+	 *
+	 * @return mixed[]
+	 *
+	 * @since 21.0.0
+	 */
+	public function fetchAll(int $fetchMode = PDO::FETCH_ASSOC): array;
+
+	/**
+	 * @return mixed
+	 *
+	 * @since 21.0.0
+	 * @deprecated 21.0.0 use \OCP\DB\IResult::fetchOne
+	 */
+	public function fetchColumn();
+
+	/**
+	 * @param int $columnIndex
+	 *
+	 * @return false|mixed
+	 *
+	 * @since 21.0.0
+	 */
+	public function fetchOne();
+
+	/**
+	 * @return int
+	 *
+	 * @since 21.0.0
+	 */
+	public function rowCount(): int;
+}
diff --git a/lib/public/DB/QueryBuilder/IQueryBuilder.php b/lib/public/DB/QueryBuilder/IQueryBuilder.php
index b4255f95834..8fcbd6c3276 100644
--- a/lib/public/DB/QueryBuilder/IQueryBuilder.php
+++ b/lib/public/DB/QueryBuilder/IQueryBuilder.php
@@ -29,6 +29,7 @@
 namespace OCP\DB\QueryBuilder;
 
 use Doctrine\DBAL\Connection;
+use OCP\DB\IResult;
 
 /**
  * This class provides a wrapper around Doctrine's QueryBuilder
@@ -148,7 +149,11 @@ interface IQueryBuilder {
 	 * Uses {@see Connection::executeQuery} for select statements and {@see Connection::executeUpdate}
 	 * for insert, update and delete statements.
 	 *
-	 * @return \Doctrine\DBAL\Driver\Statement|int
+	 * Warning: until Nextcloud 20, this method could return a \Doctrine\DBAL\Driver\Statement but since
+	 *          that interface changed in a breaking way the adapter \OCP\DB\QueryBuilder\IStatement is returned
+	 *          to bridge old code to the new API
+	 *
+	 * @return IResult|int
 	 * @since 8.2.0
 	 */
 	public function execute();
diff --git a/lib/public/IDBConnection.php b/lib/public/IDBConnection.php
index 11fa301ab86..16a5f998fde 100644
--- a/lib/public/IDBConnection.php
+++ b/lib/public/IDBConnection.php
@@ -39,7 +39,10 @@
 
 namespace OCP;
 
+use Doctrine\DBAL\Exception;
 use Doctrine\DBAL\Schema\Schema;
+use OCP\DB\IPreparedStatement;
+use OCP\DB\IResult;
 use OCP\DB\QueryBuilder\IQueryBuilder;
 
 /**
@@ -68,10 +71,11 @@ interface IDBConnection {
 	 * @param string $sql the sql query with ? placeholder for params
 	 * @param int $limit the maximum number of rows
 	 * @param int $offset from which row we want to start
-	 * @return \Doctrine\DBAL\Driver\Statement The prepared statement.
+	 * @return IPreparedStatement The prepared statement.
 	 * @since 6.0.0
+	 * @throws Exception since 21.0.0
 	 */
-	public function prepare($sql, $limit = null, $offset = null);
+	public function prepare($sql, $limit = null, $offset = null): IPreparedStatement;
 
 	/**
 	 * Executes an, optionally parameterized, SQL query.
@@ -82,10 +86,11 @@ interface IDBConnection {
 	 * @param string $sql The SQL query to execute.
 	 * @param string[] $params The parameters to bind to the query, if any.
 	 * @param array $types The types the previous parameters are in.
-	 * @return \Doctrine\DBAL\Driver\Statement The executed statement.
+	 * @return IResult The executed statement.
 	 * @since 8.0.0
+	 * @throws Exception since 21.0.0
 	 */
-	public function executeQuery($sql, array $params = [], $types = []);
+	public function executeQuery(string $sql, array $params = [], $types = []): IResult;
 
 	/**
 	 * Executes an SQL INSERT/UPDATE/DELETE query with the given parameters
@@ -96,12 +101,12 @@ interface IDBConnection {
 	 * @param string $sql The SQL query.
 	 * @param array $params The query parameters.
 	 * @param array $types The parameter types.
-	 * @return integer The number of affected rows.
+	 * @return int The number of affected rows.
 	 * @since 8.0.0
 	 *
 	 * @deprecated 21.0.0 use executeStatement
 	 */
-	public function executeUpdate($sql, array $params = [], array $types = []);
+	public function executeUpdate(string $sql, array $params = [], array $types = []): int;
 
 	/**
 	 * Executes an SQL INSERT/UPDATE/DELETE query with the given parameters
@@ -112,18 +117,20 @@ interface IDBConnection {
 	 * @param string $sql The SQL query.
 	 * @param array $params The query parameters.
 	 * @param array $types The parameter types.
-	 * @return integer The number of affected rows.
+	 * @return int The number of affected rows.
 	 * @since 21.0.0
 	 */
-	public function executeStatement($sql, array $params = [], array $types = []);
+	public function executeStatement($sql, array $params = [], array $types = []): int;
 
 	/**
 	 * Used to get the id of the just inserted element
 	 * @param string $table the name of the table where we inserted the item
 	 * @return int the id of the inserted element
 	 * @since 6.0.0
+	 * @throws Exception since 21.0.0
+	 * @deprecated 21.0.0 use \OCP\DB\QueryBuilder\IQueryBuilder::getLastInsertId
 	 */
-	public function lastInsertId($table = null);
+	public function lastInsertId(string $table): int;
 
 	/**
 	 * Insert a row if the matching row does not exists. To accomplish proper race condition avoidance
@@ -136,11 +143,11 @@ interface IDBConnection {
 	 *				If this is null or an empty array, all keys of $input will be compared
 	 *				Please note: text fields (clob) must not be used in the compare array
 	 * @return int number of inserted rows
-	 * @throws \Doctrine\DBAL\DBALException
+	 * @throws Exception
 	 * @since 6.0.0 - parameter $compare was added in 8.1.0, return type changed from boolean in 8.1.0
 	 * @deprecated 15.0.0 - use unique index and "try { $db->insert() } catch (UniqueConstraintViolationException $e) {}" instead, because it is more reliable and does not have the risk for deadlocks - see https://github.com/nextcloud/server/pull/12371
 	 */
-	public function insertIfNotExist($table, $input, array $compare = null);
+	public function insertIfNotExist(string $table, array $input, array $compare = null);
 
 
 	/**
@@ -164,11 +171,11 @@ interface IDBConnection {
 	 * @param array $values (column name => value)
 	 * @param array $updatePreconditionValues ensure values match preconditions (column name => value)
 	 * @return int number of new rows
-	 * @throws \Doctrine\DBAL\DBALException
+	 * @throws Exception
 	 * @throws PreconditionNotMetException
 	 * @since 9.0.0
 	 */
-	public function setValues($table, array $keys, array $values, array $updatePreconditionValues = []);
+	public function setValues($table, array $keys, array $values, array $updatePreconditionValues = []): int;
 
 	/**
 	 * Create an exclusive read+write lock on a table
@@ -180,20 +187,21 @@ interface IDBConnection {
 	 * @param string $tableName
 	 * @since 9.1.0
 	 */
-	public function lockTable($tableName);
+	public function lockTable($tableName): void;
 
 	/**
 	 * Release a previous acquired lock again
 	 *
 	 * @since 9.1.0
 	 */
-	public function unlockTable();
+	public function unlockTable(): void;
 
 	/**
 	 * Start a transaction
 	 * @since 6.0.0
+	 * @throws Exception since 21.0.0
 	 */
-	public function beginTransaction();
+	public function beginTransaction(): void;
 
 	/**
 	 * Check if a transaction is active
@@ -201,32 +209,36 @@ interface IDBConnection {
 	 * @return bool
 	 * @since 8.2.0
 	 */
-	public function inTransaction();
+	public function inTransaction(): bool;
 
 	/**
 	 * Commit the database changes done during a transaction that is in progress
 	 * @since 6.0.0
+	 * @throws Exception since 21.0.0
 	 */
-	public function commit();
+	public function commit(): void;
 
 	/**
 	 * Rollback the database changes done during a transaction that is in progress
 	 * @since 6.0.0
+	 * @throws Exception since 21.0.0
 	 */
-	public function rollBack();
+	public function rollBack(): void;
 
 	/**
 	 * Gets the error code and message as a string for logging
 	 * @return string
 	 * @since 6.0.0
+	 * @deprecated 21.0.0 doesn't return anything meaningful
 	 */
-	public function getError();
+	public function getError(): string;
 
 	/**
 	 * Fetch the SQLSTATE associated with the last database operation.
 	 *
 	 * @return integer The last error code.
 	 * @since 8.0.0
+	 * @deprecated 21.0.0 doesn't return anything anymore
 	 */
 	public function errorCode();
 
@@ -235,6 +247,7 @@ interface IDBConnection {
 	 *
 	 * @return array The last error information.
 	 * @since 8.0.0
+	 * @deprecated 21.0.0 doesn't return anything anymore
 	 */
 	public function errorInfo();
 
@@ -244,20 +257,20 @@ interface IDBConnection {
 	 * @return bool
 	 * @since 8.0.0
 	 */
-	public function connect();
+	public function connect(): bool;
 
 	/**
 	 * Close the database connection
 	 * @since 8.0.0
 	 */
-	public function close();
+	public function close(): void;
 
 	/**
 	 * Quotes a given input parameter.
 	 *
 	 * @param mixed $input Parameter to be quoted.
 	 * @param int $type Type of the parameter.
-	 * @return string The quoted parameter.
+	 * @return mixed The quoted parameter.
 	 * @since 8.0.0
 	 */
 	public function quote($input, $type = IQueryBuilder::PARAM_STR);
@@ -277,7 +290,7 @@ interface IDBConnection {
 	 * @param string $table table name without the prefix
 	 * @since 8.0.0
 	 */
-	public function dropTable($table);
+	public function dropTable(string $table): void;
 
 	/**
 	 * Check if a table exists
@@ -286,7 +299,7 @@ interface IDBConnection {
 	 * @return bool
 	 * @since 8.0.0
 	 */
-	public function tableExists($table);
+	public function tableExists(string $table): bool;
 
 	/**
 	 * Escape a parameter to be used in a LIKE query
@@ -295,7 +308,7 @@ interface IDBConnection {
 	 * @return string
 	 * @since 9.0.0
 	 */
-	public function escapeLikeParameter($param);
+	public function escapeLikeParameter(string $param): string;
 
 	/**
 	 * Check whether or not the current database support 4byte wide unicode
@@ -303,7 +316,7 @@ interface IDBConnection {
 	 * @return bool
 	 * @since 11.0.0
 	 */
-	public function supports4ByteText();
+	public function supports4ByteText(): bool;
 
 	/**
 	 * Create the schema of the connected database
@@ -311,7 +324,7 @@ interface IDBConnection {
 	 * @return Schema
 	 * @since 13.0.0
 	 */
-	public function createSchema();
+	public function createSchema(): Schema;
 
 	/**
 	 * Migrate the database to the given schema
@@ -319,5 +332,5 @@ interface IDBConnection {
 	 * @param Schema $toSchema
 	 * @since 13.0.0
 	 */
-	public function migrateToSchema(Schema $toSchema);
+	public function migrateToSchema(Schema $toSchema): void;
 }
diff --git a/tests/lib/AppConfigTest.php b/tests/lib/AppConfigTest.php
index d2643d599f3..d4ae66cb2f1 100644
--- a/tests/lib/AppConfigTest.php
+++ b/tests/lib/AppConfigTest.php
@@ -10,6 +10,7 @@
 namespace Test;
 
 use OC\AppConfig;
+use OC\DB\Connection;
 use OCP\IConfig;
 
 /**
@@ -23,7 +24,7 @@ class AppConfigTest extends TestCase {
 	/** @var \OCP\IAppConfig */
 	protected $appConfig;
 
-	/** @var \OCP\IDBConnection */
+	/** @var Connection */
 	protected $connection;
 
 	protected $originalConfig;
@@ -31,7 +32,7 @@ class AppConfigTest extends TestCase {
 	protected function setUp(): void {
 		parent::setUp();
 
-		$this->connection = \OC::$server->getDatabaseConnection();
+		$this->connection = \OC::$server->get(Connection::class);
 		$sql = $this->connection->getQueryBuilder();
 		$sql->select('*')
 			->from('appconfig');
@@ -138,7 +139,7 @@ class AppConfigTest extends TestCase {
 	}
 
 	public function testGetApps() {
-		$config = new \OC\AppConfig(\OC::$server->getDatabaseConnection());
+		$config = new \OC\AppConfig(\OC::$server->get(Connection::class));
 
 		$this->assertEqualsCanonicalizing([
 			'anotherapp',
@@ -149,7 +150,7 @@ class AppConfigTest extends TestCase {
 	}
 
 	public function testGetKeys() {
-		$config = new \OC\AppConfig(\OC::$server->getDatabaseConnection());
+		$config = new \OC\AppConfig(\OC::$server->get(Connection::class));
 
 		$keys = $config->getKeys('testapp');
 		$this->assertEqualsCanonicalizing([
@@ -162,7 +163,7 @@ class AppConfigTest extends TestCase {
 	}
 
 	public function testGetValue() {
-		$config = new \OC\AppConfig(\OC::$server->getDatabaseConnection());
+		$config = new \OC\AppConfig(\OC::$server->get(Connection::class));
 
 		$value = $config->getValue('testapp', 'installed_version');
 		$this->assertConfigKey('testapp', 'installed_version', $value);
@@ -175,7 +176,7 @@ class AppConfigTest extends TestCase {
 	}
 
 	public function testHasKey() {
-		$config = new \OC\AppConfig(\OC::$server->getDatabaseConnection());
+		$config = new \OC\AppConfig(\OC::$server->get(Connection::class));
 
 		$this->assertTrue($config->hasKey('testapp', 'installed_version'));
 		$this->assertFalse($config->hasKey('testapp', 'nonexistant'));
@@ -183,13 +184,13 @@ class AppConfigTest extends TestCase {
 	}
 
 	public function testSetValueUpdate() {
-		$config = new \OC\AppConfig(\OC::$server->getDatabaseConnection());
+		$config = new \OC\AppConfig(\OC::$server->get(Connection::class));
 
 		$this->assertEquals('1.2.3', $config->getValue('testapp', 'installed_version'));
 		$this->assertConfigKey('testapp', 'installed_version', '1.2.3');
 
 		$wasModified = $config->setValue('testapp', 'installed_version', '1.2.3');
-		if (!(\OC::$server->getDatabaseConnection() instanceof \OC\DB\OracleConnection)) {
+		if (!(\OC::$server->get(Connection::class) instanceof \OC\DB\OracleConnection)) {
 			$this->assertFalse($wasModified);
 		}
 
@@ -207,7 +208,7 @@ class AppConfigTest extends TestCase {
 	}
 
 	public function testSetValueInsert() {
-		$config = new \OC\AppConfig(\OC::$server->getDatabaseConnection());
+		$config = new \OC\AppConfig(\OC::$server->get(Connection::class));
 
 		$this->assertFalse($config->hasKey('someapp', 'somekey'));
 		$this->assertNull($config->getValue('someapp', 'somekey'));
@@ -219,13 +220,13 @@ class AppConfigTest extends TestCase {
 		$this->assertConfigKey('someapp', 'somekey', 'somevalue');
 
 		$wasInserted = $config->setValue('someapp', 'somekey', 'somevalue');
-		if (!(\OC::$server->getDatabaseConnection() instanceof \OC\DB\OracleConnection)) {
+		if (!(\OC::$server->get(Connection::class) instanceof \OC\DB\OracleConnection)) {
 			$this->assertFalse($wasInserted);
 		}
 	}
 
 	public function testDeleteKey() {
-		$config = new \OC\AppConfig(\OC::$server->getDatabaseConnection());
+		$config = new \OC\AppConfig(\OC::$server->get(Connection::class));
 
 		$this->assertTrue($config->hasKey('testapp', 'deletethis'));
 
@@ -247,7 +248,7 @@ class AppConfigTest extends TestCase {
 	}
 
 	public function testDeleteApp() {
-		$config = new \OC\AppConfig(\OC::$server->getDatabaseConnection());
+		$config = new \OC\AppConfig(\OC::$server->get(Connection::class));
 
 		$this->assertTrue($config->hasKey('someapp', 'otherkey'));
 
@@ -267,7 +268,7 @@ class AppConfigTest extends TestCase {
 	}
 
 	public function testGetValuesNotAllowed() {
-		$config = new \OC\AppConfig(\OC::$server->getDatabaseConnection());
+		$config = new \OC\AppConfig(\OC::$server->get(Connection::class));
 
 		$this->assertFalse($config->getValues('testapp', 'enabled'));
 
@@ -275,7 +276,7 @@ class AppConfigTest extends TestCase {
 	}
 
 	public function testGetValues() {
-		$config = new \OC\AppConfig(\OC::$server->getDatabaseConnection());
+		$config = new \OC\AppConfig(\OC::$server->get(Connection::class));
 
 		$sql = \OC::$server->getDatabaseConnection()->getQueryBuilder();
 		$sql->select(['configkey', 'configvalue'])
@@ -311,7 +312,7 @@ class AppConfigTest extends TestCase {
 	public function testGetFilteredValues() {
 		/** @var \OC\AppConfig|\PHPUnit\Framework\MockObject\MockObject $config */
 		$config = $this->getMockBuilder(\OC\AppConfig::class)
-			->setConstructorArgs([\OC::$server->getDatabaseConnection()])
+			->setConstructorArgs([\OC::$server->get(Connection::class)])
 			->setMethods(['getValues'])
 			->getMock();
 
@@ -333,8 +334,8 @@ class AppConfigTest extends TestCase {
 	}
 
 	public function testSettingConfigParallel() {
-		$appConfig1 = new \OC\AppConfig(\OC::$server->getDatabaseConnection());
-		$appConfig2 = new \OC\AppConfig(\OC::$server->getDatabaseConnection());
+		$appConfig1 = new \OC\AppConfig(\OC::$server->get(Connection::class));
+		$appConfig2 = new \OC\AppConfig(\OC::$server->get(Connection::class));
 		$appConfig1->getValue('testapp', 'foo', 'v1');
 		$appConfig2->getValue('testapp', 'foo', 'v1');
 
diff --git a/tests/lib/AppFramework/Db/MapperTestUtility.php b/tests/lib/AppFramework/Db/MapperTestUtility.php
index b25ff9f3e16..e17b875e4c4 100644
--- a/tests/lib/AppFramework/Db/MapperTestUtility.php
+++ b/tests/lib/AppFramework/Db/MapperTestUtility.php
@@ -23,12 +23,15 @@
 
 namespace Test\AppFramework\Db;
 
+use OCP\DB\IPreparedStatement;
+use OCP\DB\IResult;
+
 /**
  * Simple utility class for testing mappers
  */
 abstract class MapperTestUtility extends \Test\TestCase {
 	protected $db;
-	private $query;
+	private $statement;
 	private $queryAt;
 	private $prepareAt;
 	private $fetchAt;
@@ -47,7 +50,7 @@ abstract class MapperTestUtility extends \Test\TestCase {
 			->disableOriginalConstructor()
 			->getMock();
 
-		$this->query = $this->createMock('\PDOStatement');
+		$this->statement = $this->createMock(IPreparedStatement::class);
 		$this->queryAt = 0;
 		$this->prepareAt = 0;
 		$this->iterators = [];
@@ -94,26 +97,26 @@ abstract class MapperTestUtility extends \Test\TestCase {
 			$this->db->expects($this->at($this->prepareAt))
 				->method('prepare')
 				->with($this->equalTo($sql))
-				->will(($this->returnValue($this->query)));
+				->will(($this->returnValue($this->statement)));
 		} elseif ($limit !== null && $offset === null) {
 			$this->db->expects($this->at($this->prepareAt))
 				->method('prepare')
 				->with($this->equalTo($sql), $this->equalTo($limit))
-				->will(($this->returnValue($this->query)));
+				->will(($this->returnValue($this->statement)));
 		} elseif ($limit === null && $offset !== null) {
 			$this->db->expects($this->at($this->prepareAt))
 				->method('prepare')
 				->with($this->equalTo($sql),
 					$this->equalTo(null),
 					$this->equalTo($offset))
-				->will(($this->returnValue($this->query)));
+				->will(($this->returnValue($this->statement)));
 		} else {
 			$this->db->expects($this->at($this->prepareAt))
 				->method('prepare')
 				->with($this->equalTo($sql),
 					$this->equalTo($limit),
 					$this->equalTo($offset))
-				->will(($this->returnValue($this->query)));
+				->will(($this->returnValue($this->statement)));
 		}
 
 		$this->iterators[] = new ArgumentIterator($returnRows);
@@ -121,7 +124,7 @@ abstract class MapperTestUtility extends \Test\TestCase {
 		$iterators = $this->iterators;
 		$fetchAt = $this->fetchAt;
 
-		$this->query->expects($this->any())
+		$this->statement->expects($this->any())
 			->method('fetch')
 			->willReturnCallback(
 				function () use ($iterators, $fetchAt) {
@@ -141,7 +144,7 @@ abstract class MapperTestUtility extends \Test\TestCase {
 		if ($this->isAssocArray($arguments)) {
 			foreach ($arguments as $key => $argument) {
 				$pdoConstant = $this->getPDOType($argument);
-				$this->query->expects($this->at($this->queryAt))
+				$this->statement->expects($this->at($this->queryAt))
 					->method('bindValue')
 					->with($this->equalTo($key),
 						$this->equalTo($argument),
@@ -152,7 +155,7 @@ abstract class MapperTestUtility extends \Test\TestCase {
 			$index = 1;
 			foreach ($arguments as $argument) {
 				$pdoConstant = $this->getPDOType($argument);
-				$this->query->expects($this->at($this->queryAt))
+				$this->statement->expects($this->at($this->queryAt))
 					->method('bindValue')
 					->with($this->equalTo($index),
 						$this->equalTo($argument),
@@ -162,9 +165,10 @@ abstract class MapperTestUtility extends \Test\TestCase {
 			}
 		}
 
-		$this->query->expects($this->at($this->queryAt))
+		$this->statement->expects($this->at($this->queryAt))
 			->method('execute')
 			->willReturnCallback(function ($sql, $p = null, $o = null, $s = null) {
+				return $this->createMock(IResult::class);
 			});
 		$this->queryAt++;
 
@@ -175,7 +179,7 @@ abstract class MapperTestUtility extends \Test\TestCase {
 		} else {
 			$closing = $this->any();
 		}
-		$this->query->expects($closing)->method('closeCursor');
+		$this->statement->expects($closing)->method('closeCursor');
 		$this->queryAt++;
 
 		$this->prepareAt++;
diff --git a/tests/lib/DB/ConnectionTest.php b/tests/lib/DB/ConnectionTest.php
index cab6133c3c0..d628d9814e0 100644
--- a/tests/lib/DB/ConnectionTest.php
+++ b/tests/lib/DB/ConnectionTest.php
@@ -44,7 +44,7 @@ class ConnectionTest extends \Test\TestCase {
 
 	protected function setUp(): void {
 		parent::setUp();
-		$this->connection = \OC::$server->getDatabaseConnection();
+		$this->connection = \OC::$server->get(\OC\DB\Connection::class);
 	}
 
 	protected function tearDown(): void {
@@ -234,7 +234,7 @@ class ConnectionTest extends \Test\TestCase {
 		$query = $this->connection->prepare('SELECT * FROM `*PREFIX*table`');
 		$result = $query->execute();
 		$this->assertTrue((bool)$result);
-		$this->assertEquals(7, count($query->fetchAll()));
+		$this->assertEquals(7, count($result->fetchAll()));
 	}
 
 	public function testInsertIfNotExistNull() {
@@ -263,7 +263,7 @@ class ConnectionTest extends \Test\TestCase {
 		$query = $this->connection->prepare('SELECT * FROM `*PREFIX*table`');
 		$result = $query->execute();
 		$this->assertTrue((bool)$result);
-		$this->assertEquals(2, count($query->fetchAll()));
+		$this->assertEquals(2, count($result->fetchAll()));
 	}
 
 	public function testInsertIfNotExistDonTOverwrite() {
@@ -278,11 +278,10 @@ class ConnectionTest extends \Test\TestCase {
 		// Normal test to have same known data inserted.
 		$query = $this->connection->prepare('INSERT INTO `*PREFIX*table` (`textfield`, `clobfield`) VALUES (?, ?)');
 		$result = $query->execute([$fullName, $uri]);
-		$this->assertEquals(1, $result);
+		$this->assertEquals(1, $result->rowCount());
 		$query = $this->connection->prepare('SELECT `textfield`, `clobfield` FROM `*PREFIX*table` WHERE `clobfield` = ?');
 		$result = $query->execute([$uri]);
-		$this->assertTrue($result);
-		$rowset = $query->fetchAll();
+		$rowset = $result->fetchAll();
 		$this->assertEquals(1, count($rowset));
 		$this->assertArrayHasKey('textfield', $rowset[0]);
 		$this->assertEquals($fullName, $rowset[0]['textfield']);
@@ -297,10 +296,9 @@ class ConnectionTest extends \Test\TestCase {
 
 		$query = $this->connection->prepare('SELECT `textfield`, `clobfield` FROM `*PREFIX*table` WHERE `clobfield` = ?');
 		$result = $query->execute([$uri]);
-		$this->assertTrue($result);
 		// Test that previously inserted data isn't overwritten
 		// And that a new row hasn't been inserted.
-		$rowset = $query->fetchAll();
+		$rowset = $result->fetchAll();
 		$this->assertEquals(1, count($rowset));
 		$this->assertArrayHasKey('textfield', $rowset[0]);
 		$this->assertEquals($fullName, $rowset[0]['textfield']);
diff --git a/tests/lib/DB/DBSchemaTest.php b/tests/lib/DB/DBSchemaTest.php
index 9f575a75da6..4f24c3f67aa 100644
--- a/tests/lib/DB/DBSchemaTest.php
+++ b/tests/lib/DB/DBSchemaTest.php
@@ -64,7 +64,6 @@ class DBSchemaTest extends TestCase {
 	public function testSchema() {
 		$this->doTestSchemaCreating();
 		$this->doTestSchemaChanging();
-		$this->doTestSchemaDumping();
 		$this->doTestSchemaRemoving();
 	}
 
@@ -79,14 +78,6 @@ class DBSchemaTest extends TestCase {
 		$this->assertTableExist($this->table2);
 	}
 
-	public function doTestSchemaDumping() {
-		$outfile = $this->tempManager->getTemporaryFile();
-		OC_DB::getDbStructure($outfile);
-		$content = file_get_contents($outfile);
-		$this->assertStringContainsString($this->table1, $content);
-		$this->assertStringContainsString($this->table2, $content);
-	}
-
 	public function doTestSchemaRemoving() {
 		OC_DB::removeDBStructure($this->schema_file);
 		$this->assertTableNotExist($this->table1);
diff --git a/tests/lib/DB/MDB2SchemaManagerTest.php b/tests/lib/DB/MDB2SchemaManagerTest.php
index 18af9716502..693de746b5e 100644
--- a/tests/lib/DB/MDB2SchemaManagerTest.php
+++ b/tests/lib/DB/MDB2SchemaManagerTest.php
@@ -30,7 +30,7 @@ class MDB2SchemaManagerTest extends \Test\TestCase {
 	}
 
 	public function testAutoIncrement() {
-		$connection = \OC::$server->getDatabaseConnection();
+		$connection = \OC::$server->get(\OC\DB\Connection::class);
 		if ($connection->getDatabasePlatform() instanceof OraclePlatform) {
 			$this->markTestSkipped('Adding auto increment columns in Oracle is not supported.');
 		}
diff --git a/tests/lib/DB/MDB2SchemaReaderTest.php b/tests/lib/DB/MDB2SchemaReaderTest.php
index b3dd98fd6b7..1e7d3a20b7c 100644
--- a/tests/lib/DB/MDB2SchemaReaderTest.php
+++ b/tests/lib/DB/MDB2SchemaReaderTest.php
@@ -9,7 +9,7 @@
 
 namespace Test\DB;
 
-use Doctrine\DBAL\Platforms\MySqlPlatform;
+use Doctrine\DBAL\Platforms\MySQLPlatform;
 use Doctrine\DBAL\Schema\Schema;
 use OC\DB\MDB2SchemaReader;
 use OCP\IConfig;
@@ -50,7 +50,7 @@ class MDB2SchemaReaderTest extends TestCase {
 	}
 
 	public function testRead() {
-		$reader = new MDB2SchemaReader($this->getConfig(), new MySqlPlatform());
+		$reader = new MDB2SchemaReader($this->getConfig(), new MySQLPlatform());
 		$schema = $reader->loadSchemaFromFile(__DIR__ . '/testschema.xml', new Schema());
 		$this->assertCount(1, $schema->getTables());
 
diff --git a/tests/lib/DB/MigratorTest.php b/tests/lib/DB/MigratorTest.php
index 52b0b0ff03e..539eb404bbf 100644
--- a/tests/lib/DB/MigratorTest.php
+++ b/tests/lib/DB/MigratorTest.php
@@ -9,7 +9,7 @@
 
 namespace Test\DB;
 
-use Doctrine\DBAL\DBALException;
+use Doctrine\DBAL\Exception;
 use Doctrine\DBAL\Platforms\OraclePlatform;
 use Doctrine\DBAL\Schema\Schema;
 use Doctrine\DBAL\Schema\SchemaConfig;
@@ -49,7 +49,7 @@ class MigratorTest extends \Test\TestCase {
 		parent::setUp();
 
 		$this->config = \OC::$server->getConfig();
-		$this->connection = \OC::$server->getDatabaseConnection();
+		$this->connection = \OC::$server->get(\OC\DB\Connection::class);
 		if ($this->connection->getDatabasePlatform() instanceof OraclePlatform) {
 			$this->markTestSkipped('DB migration tests are not supported on OCI');
 		}
@@ -66,12 +66,12 @@ class MigratorTest extends \Test\TestCase {
 		// Try to delete if exists (IF EXISTS NOT SUPPORTED IN ORACLE)
 		try {
 			$this->connection->exec('DROP TABLE ' . $this->connection->quoteIdentifier($this->tableNameTmp));
-		} catch (\Doctrine\DBAL\DBALException $e) {
+		} catch (Exception $e) {
 		}
 
 		try {
 			$this->connection->exec('DROP TABLE ' . $this->connection->quoteIdentifier($this->tableName));
-		} catch (\Doctrine\DBAL\DBALException $e) {
+		} catch (Exception $e) {
 		}
 		parent::tearDown();
 	}
@@ -125,9 +125,9 @@ class MigratorTest extends \Test\TestCase {
 		return $this->connection->getDriver() instanceof \Doctrine\DBAL\Driver\PDOSqlite\Driver;
 	}
 
-	
+
 	public function testDuplicateKeyUpgrade() {
-		$this->expectException(\OC\DB\MigrationException::class);
+		$this->expectException(Exception\UniqueConstraintViolationException::class);
 
 		if ($this->isSQLite()) {
 			$this->markTestSkipped('sqlite does not throw errors when creating a new key on existing data');
@@ -140,8 +140,12 @@ class MigratorTest extends \Test\TestCase {
 		$this->connection->insert($this->tableName, ['id' => 2, 'name' => 'bar']);
 		$this->connection->insert($this->tableName, ['id' => 2, 'name' => 'qwerty']);
 
-		$migrator->checkMigrate($endSchema);
-		$this->fail('checkMigrate should have failed');
+		try {
+			$migrator->migrate($endSchema);
+		} catch (Exception\UniqueConstraintViolationException $e) {
+			$this->connection->rollBack();
+			throw $e;
+		}
 	}
 
 	public function testChangeToString() {
@@ -156,7 +160,6 @@ class MigratorTest extends \Test\TestCase {
 		$this->connection->insert($this->tableName, ['id' => 2, 'name' => 'bar']);
 		$this->connection->insert($this->tableName, ['id' => 3, 'name' => 'qwerty']);
 
-		$migrator->checkMigrate($endSchema);
 		$migrator->migrate($endSchema);
 		$this->addToAssertionCount(1);
 
@@ -181,7 +184,6 @@ class MigratorTest extends \Test\TestCase {
 		$this->connection->insert($this->tableName, ['id' => 2, 'name' => 'bar']);
 		$this->connection->insert($this->tableName, ['id' => 3, 'name' => 'qwerty']);
 
-		$migrator->checkMigrate($endSchema);
 		$migrator->migrate($endSchema);
 		$this->addToAssertionCount(1);
 	}
@@ -200,7 +202,6 @@ class MigratorTest extends \Test\TestCase {
 		$this->connection->insert($this->tableName, ['id' => 2, 'name' => 'bar']);
 		$this->connection->insert($this->tableName, ['id' => 3, 'name' => 'qwerty']);
 
-		$migrator->checkMigrate($endSchema);
 		$migrator->migrate($endSchema);
 		$this->addToAssertionCount(1);
 
@@ -219,7 +220,7 @@ class MigratorTest extends \Test\TestCase {
 		try {
 			$this->connection->insert($this->tableName, ['id' => 2, 'name' => 'qwerty']);
 			$this->fail('Expected duplicate key insert to fail');
-		} catch (DBALException $e) {
+		} catch (Exception $e) {
 			$this->addToAssertionCount(1);
 		}
 	}
@@ -239,7 +240,6 @@ class MigratorTest extends \Test\TestCase {
 		$migrator = $this->manager->getMigrator();
 		$migrator->migrate($startSchema);
 
-		$migrator->checkMigrate($endSchema);
 		$migrator->migrate($endSchema);
 
 		$this->addToAssertionCount(1);
@@ -261,7 +261,6 @@ class MigratorTest extends \Test\TestCase {
 		$migrator = $this->manager->getMigrator();
 		$migrator->migrate($startSchema);
 
-		$migrator->checkMigrate($endSchema);
 		$migrator->migrate($endSchema);
 
 		$this->addToAssertionCount(1);
diff --git a/tests/lib/DB/MySqlMigrationTest.php b/tests/lib/DB/MySqlMigrationTest.php
index 36ab8ef7319..38cb64916ec 100644
--- a/tests/lib/DB/MySqlMigrationTest.php
+++ b/tests/lib/DB/MySqlMigrationTest.php
@@ -24,7 +24,7 @@ class MySqlMigrationTest extends \Test\TestCase {
 	protected function setUp(): void {
 		parent::setUp();
 
-		$this->connection = \OC::$server->getDatabaseConnection();
+		$this->connection = \OC::$server->get(\OC\DB\Connection::class);
 		if (!$this->connection->getDatabasePlatform() instanceof \Doctrine\DBAL\Platforms\MySqlPlatform) {
 			$this->markTestSkipped("Test only relevant on MySql");
 		}
diff --git a/tests/lib/DB/OCPostgreSqlPlatformTest.php b/tests/lib/DB/OCPostgreSqlPlatformTest.php
index 62a2fc34712..334a2ecc778 100644
--- a/tests/lib/DB/OCPostgreSqlPlatformTest.php
+++ b/tests/lib/DB/OCPostgreSqlPlatformTest.php
@@ -21,7 +21,7 @@
 
 namespace Test\DB;
 
-use Doctrine\DBAL\Platforms\PostgreSqlPlatform;
+use Doctrine\DBAL\Platforms\PostgreSQL100Platform;
 use Doctrine\DBAL\Schema\Comparator;
 use Doctrine\DBAL\Schema\Schema;
 use Doctrine\DBAL\Types\Types;
@@ -38,7 +38,7 @@ use Doctrine\DBAL\Types\Types;
  */
 class OCPostgreSqlPlatformTest extends \Test\TestCase {
 	public function testAlterBigint() {
-		$platform = new PostgreSqlPlatform();
+		$platform = new PostgreSQL100Platform();
 		$sourceSchema = new Schema();
 		$targetSchema = new Schema();
 
diff --git a/tests/lib/DB/QueryBuilder/ExpressionBuilderDBTest.php b/tests/lib/DB/QueryBuilder/ExpressionBuilderDBTest.php
index 8fd86a638fe..d7f6b4ac115 100644
--- a/tests/lib/DB/QueryBuilder/ExpressionBuilderDBTest.php
+++ b/tests/lib/DB/QueryBuilder/ExpressionBuilderDBTest.php
@@ -68,7 +68,7 @@ class ExpressionBuilderDBTest extends TestCase {
 			->where($query->expr()->like($query->createNamedParameter($param1), $query->createNamedParameter($param2)));
 
 		$result = $query->execute();
-		$column = $result->fetchColumn();
+		$column = $result->fetchOne();
 		$result->closeCursor();
 		$this->assertEquals($match, $column);
 	}
@@ -105,7 +105,7 @@ class ExpressionBuilderDBTest extends TestCase {
 			->where($query->expr()->iLike($query->createNamedParameter($param1), $query->createNamedParameter($param2)));
 
 		$result = $query->execute();
-		$column = $result->fetchColumn();
+		$column = $result->fetchOne();
 		$result->closeCursor();
 		$this->assertEquals($match, $column);
 	}
diff --git a/tests/lib/DB/QueryBuilder/ExpressionBuilderTest.php b/tests/lib/DB/QueryBuilder/ExpressionBuilderTest.php
index b3e9124e7de..2a3a4e9a9c1 100644
--- a/tests/lib/DB/QueryBuilder/ExpressionBuilderTest.php
+++ b/tests/lib/DB/QueryBuilder/ExpressionBuilderTest.php
@@ -40,19 +40,23 @@ class ExpressionBuilderTest extends TestCase {
 	/** @var DoctrineExpressionBuilder */
 	protected $doctrineExpressionBuilder;
 
-	/** @var \Doctrine\DBAL\Connection|\OCP\IDBConnection */
+	/** @var \OCP\IDBConnection */
 	protected $connection;
 
+	/** @var \Doctrine\DBAL\Connection */
+	protected $internalConnection;
+
 	protected function setUp(): void {
 		parent::setUp();
 
 		$this->connection = \OC::$server->getDatabaseConnection();
+		$this->internalConnection = \OC::$server->get(\OC\DB\Connection::class);
 
 		$queryBuilder = $this->createMock(IQueryBuilder::class);
 
 		$this->expressionBuilder = new ExpressionBuilder($this->connection, $queryBuilder);
 
-		$this->doctrineExpressionBuilder = new DoctrineExpressionBuilder($this->connection);
+		$this->doctrineExpressionBuilder = new DoctrineExpressionBuilder($this->internalConnection);
 	}
 
 	public function dataComparison() {
diff --git a/tests/lib/DB/QueryBuilder/FunctionBuilderTest.php b/tests/lib/DB/QueryBuilder/FunctionBuilderTest.php
index fad991bfa90..71ae3d5c7f6 100644
--- a/tests/lib/DB/QueryBuilder/FunctionBuilderTest.php
+++ b/tests/lib/DB/QueryBuilder/FunctionBuilderTest.php
@@ -49,7 +49,7 @@ class FunctionBuilderTest extends TestCase {
 			->setMaxResults(1);
 
 		$result = $query->execute();
-		$column = $result->fetchColumn();
+		$column = $result->fetchOne();
 		$result->closeCursor();
 		$this->assertEquals('foobar', $column);
 	}
@@ -62,7 +62,7 @@ class FunctionBuilderTest extends TestCase {
 			->setMaxResults(1);
 
 		$result = $query->execute();
-		$column = $result->fetchColumn();
+		$column = $result->fetchOne();
 		$result->closeCursor();
 		$this->assertEquals(md5('foobar'), $column);
 	}
@@ -75,7 +75,7 @@ class FunctionBuilderTest extends TestCase {
 			->setMaxResults(1);
 
 		$result = $query->execute();
-		$column = $result->fetchColumn();
+		$column = $result->fetchOne();
 		$result->closeCursor();
 		$this->assertEquals('oo', $column);
 	}
@@ -88,7 +88,7 @@ class FunctionBuilderTest extends TestCase {
 			->setMaxResults(1);
 
 		$result = $query->execute();
-		$column = $result->fetchColumn();
+		$column = $result->fetchOne();
 		$result->closeCursor();
 		$this->assertEquals('oobar', $column);
 	}
@@ -101,7 +101,7 @@ class FunctionBuilderTest extends TestCase {
 			->setMaxResults(1);
 
 		$result = $query->execute();
-		$column = $result->fetchColumn();
+		$column = $result->fetchOne();
 		$result->closeCursor();
 		$this->assertEquals('foobar', $column);
 	}
@@ -114,7 +114,7 @@ class FunctionBuilderTest extends TestCase {
 			->setMaxResults(1);
 
 		$result = $query->execute();
-		$column = $result->fetchColumn();
+		$column = $result->fetchOne();
 		$result->closeCursor();
 		$this->assertEquals(3, $column);
 	}
@@ -127,7 +127,7 @@ class FunctionBuilderTest extends TestCase {
 			->setMaxResults(1);
 
 		$result = $query->execute();
-		$column = $result->fetchColumn();
+		$column = $result->fetchOne();
 		$result->closeCursor();
 		$this->assertEquals(1, $column);
 	}
@@ -140,7 +140,7 @@ class FunctionBuilderTest extends TestCase {
 			->setMaxResults(1);
 
 		$result = $query->execute();
-		$column = $result->fetchColumn();
+		$column = $result->fetchOne();
 		$result->closeCursor();
 		$this->assertGreaterThan(1, $column);
 	}
@@ -176,7 +176,7 @@ class FunctionBuilderTest extends TestCase {
 			->setMaxResults(1);
 
 		$result = $query->execute();
-		$row = $result->fetchColumn();
+		$row = $result->fetchOne();
 		$result->closeCursor();
 		$this->assertEquals(null, $row);
 	}
@@ -192,7 +192,7 @@ class FunctionBuilderTest extends TestCase {
 			->setMaxResults(1);
 
 		$result = $query->execute();
-		$row = $result->fetchColumn();
+		$row = $result->fetchOne();
 		$result->closeCursor();
 		$this->assertEquals(null, $row);
 	}
@@ -211,7 +211,7 @@ class FunctionBuilderTest extends TestCase {
 			->setMaxResults(1);
 
 		$result = $query->execute();
-		$row = $result->fetchColumn();
+		$row = $result->fetchOne();
 		$result->closeCursor();
 		$this->assertEquals(20, $row);
 	}
@@ -230,7 +230,7 @@ class FunctionBuilderTest extends TestCase {
 			->setMaxResults(1);
 
 		$result = $query->execute();
-		$row = $result->fetchColumn();
+		$row = $result->fetchOne();
 		$result->closeCursor();
 		$this->assertEquals(10, $row);
 	}
@@ -243,7 +243,7 @@ class FunctionBuilderTest extends TestCase {
 			->setMaxResults(1);
 
 		$result = $query->execute();
-		$row = $result->fetchColumn();
+		$row = $result->fetchOne();
 		$result->closeCursor();
 		$this->assertEquals(2, $row);
 	}
@@ -256,7 +256,7 @@ class FunctionBuilderTest extends TestCase {
 			->setMaxResults(1);
 
 		$result = $query->execute();
-		$row = $result->fetchColumn();
+		$row = $result->fetchOne();
 		$result->closeCursor();
 		$this->assertEquals(1, $row);
 	}
diff --git a/tests/lib/DB/SchemaDiffTest.php b/tests/lib/DB/SchemaDiffTest.php
index 6394fa41b8e..0e5612e3b3b 100644
--- a/tests/lib/DB/SchemaDiffTest.php
+++ b/tests/lib/DB/SchemaDiffTest.php
@@ -26,6 +26,7 @@ use Doctrine\DBAL\Schema\SchemaDiff;
 use OC\DB\MDB2SchemaManager;
 use OC\DB\MDB2SchemaReader;
 use OCP\IConfig;
+use OCP\IDBConnection;
 use Test\TestCase;
 
 /**
@@ -36,8 +37,10 @@ use Test\TestCase;
  * @package Test\DB
  */
 class SchemaDiffTest extends TestCase {
-	/** @var \Doctrine\DBAL\Connection $connection */
+	/** @var IDBConnection $connection */
 	private $connection;
+	/** @var \Doctrine\DBAL\Connection $connection */
+	private $internalConnection;
 
 	/** @var MDB2SchemaManager */
 	private $manager;
@@ -57,7 +60,8 @@ class SchemaDiffTest extends TestCase {
 
 		$this->config = \OC::$server->getConfig();
 		$this->connection = \OC::$server->getDatabaseConnection();
-		$this->manager = new MDB2SchemaManager($this->connection);
+		$this->internalConnection = \OC::$server->get(\OC\DB\Connection::class);
+		$this->manager = new MDB2SchemaManager($this->internalConnection);
 		$this->testPrefix = strtolower($this->getUniqueID($this->config->getSystemValue('dbtableprefix', 'oc_'), 3));
 	}
 
@@ -79,17 +83,17 @@ class SchemaDiffTest extends TestCase {
 		$this->manager->createDbFromStructure($schemaFile);
 
 		$schemaReader = new MDB2SchemaReader($this->config, $this->connection->getDatabasePlatform());
-		$toSchema = new Schema([], [], $this->connection->getSchemaManager()->createSchemaConfig());
+		$toSchema = new Schema([], [], $this->internalConnection->getSchemaManager()->createSchemaConfig());
 		$endSchema = $schemaReader->loadSchemaFromFile($schemaFile, $toSchema);
 
 		// get the diff
 		/** @var SchemaDiff $diff */
 		$migrator = $this->manager->getMigrator();
-		$diff = $this->invokePrivate($migrator, 'getDiff', [$endSchema, $this->connection]);
+		$diff = $this->invokePrivate($migrator, 'getDiff', [$endSchema, $this->internalConnection]);
 
 		// no sql statement is expected
 		$sqls = $diff->toSql($this->connection->getDatabasePlatform());
-		$this->assertEquals([], $sqls);
+		$this->assertEmpty($sqls);
 	}
 
 	public function providesSchemaFiles() {
diff --git a/tests/lib/DB/SqliteMigrationTest.php b/tests/lib/DB/SqliteMigrationTest.php
index 480a5ebe74f..b0bf39b4035 100644
--- a/tests/lib/DB/SqliteMigrationTest.php
+++ b/tests/lib/DB/SqliteMigrationTest.php
@@ -24,14 +24,14 @@ class SqliteMigrationTest extends \Test\TestCase {
 	protected function setUp(): void {
 		parent::setUp();
 
-		$this->connection = \OC::$server->getDatabaseConnection();
+		$this->connection = \OC::$server->get(\OC\DB\Connection::class);
 		if (!$this->connection->getDatabasePlatform() instanceof \Doctrine\DBAL\Platforms\SqlitePlatform) {
 			$this->markTestSkipped("Test only relevant on Sqlite");
 		}
 
 		$dbPrefix = \OC::$server->getConfig()->getSystemValue("dbtableprefix");
 		$this->tableName = $this->getUniqueID($dbPrefix . '_enum_bit_test');
-		$this->connection->exec("CREATE TABLE $this->tableName(t0 tinyint unsigned, t1 tinyint)");
+		$this->connection->prepare("CREATE TABLE $this->tableName(t0 tinyint unsigned, t1 tinyint)")->execute();
 	}
 
 	protected function tearDown(): void {
diff --git a/tests/lib/Files/Cache/CacheTest.php b/tests/lib/Files/Cache/CacheTest.php
index a6d429798e8..d74f9cc723c 100644
--- a/tests/lib/Files/Cache/CacheTest.php
+++ b/tests/lib/Files/Cache/CacheTest.php
@@ -116,7 +116,7 @@ class CacheTest extends \Test\TestCase {
 	public function testFolder($folder) {
 		if (strpos($folder, 'F09F9890')) {
 			// 4 byte UTF doesn't work on mysql
-			$params = \OC::$server->getDatabaseConnection()->getParams();
+			$params = \OC::$server->get(\OC\DB\Connection::class)->getParams();
 			if (\OC::$server->getDatabaseConnection()->getDatabasePlatform() instanceof MySqlPlatform && $params['charset'] !== 'utf8mb4') {
 				$this->markTestSkipped('MySQL doesn\'t support 4 byte UTF-8');
 			}
diff --git a/tests/lib/Files/Config/UserMountCacheTest.php b/tests/lib/Files/Config/UserMountCacheTest.php
index 6f347a504cb..2bea4f8389a 100644
--- a/tests/lib/Files/Config/UserMountCacheTest.php
+++ b/tests/lib/Files/Config/UserMountCacheTest.php
@@ -337,7 +337,7 @@ class UserMountCacheTest extends TestCase {
 			$sql = 'SELECT `fileid` FROM `*PREFIX*filecache` WHERE `storage` = ? AND `path_hash` =?';
 			$query = $this->connection->prepare($sql);
 			$query->execute([$storageId, md5($internalPath)]);
-			return (int)$query->fetchColumn();
+			return (int)$query->fetchOne();
 		}
 		return $id;
 	}
diff --git a/tests/lib/Lock/DBLockingProviderTest.php b/tests/lib/Lock/DBLockingProviderTest.php
index 3f53589d8f1..31abd330fed 100644
--- a/tests/lib/Lock/DBLockingProviderTest.php
+++ b/tests/lib/Lock/DBLockingProviderTest.php
@@ -94,7 +94,7 @@ class DBLockingProviderTest extends LockingProvider {
 	private function getLockEntryCount() {
 		$query = $this->connection->prepare('SELECT count(*) FROM `*PREFIX*file_locks`');
 		$query->execute();
-		return $query->fetchColumn();
+		return $query->fetchOne();
 	}
 
 	protected function getLockValue($key) {
@@ -104,7 +104,7 @@ class DBLockingProviderTest extends LockingProvider {
 			->where($query->expr()->eq('key', $query->createNamedParameter($key)));
 
 		$result = $query->execute();
-		$rows = $result->fetchColumn();
+		$rows = $result->fetchOne();
 		$result->closeCursor();
 
 		return $rows;
diff --git a/tests/lib/Repair/CleanTagsTest.php b/tests/lib/Repair/CleanTagsTest.php
index a56d79f9bc6..3f3ac0bf18d 100644
--- a/tests/lib/Repair/CleanTagsTest.php
+++ b/tests/lib/Repair/CleanTagsTest.php
@@ -122,7 +122,7 @@ class CleanTagsTest extends \Test\TestCase {
 			->from($tableName)
 			->execute();
 
-		$this->assertEquals($expected, $result->fetchColumn(), $message);
+		$this->assertEquals($expected, $result->fetchOne(), $message);
 	}
 
 	/**
diff --git a/tests/lib/Repair/RepairCollationTest.php b/tests/lib/Repair/RepairCollationTest.php
index 9cba3e8e30a..35679eb8630 100644
--- a/tests/lib/Repair/RepairCollationTest.php
+++ b/tests/lib/Repair/RepairCollationTest.php
@@ -8,7 +8,6 @@
 
 namespace Test\Repair;
 
-use Doctrine\DBAL\Connection;
 use Doctrine\DBAL\Platforms\MySqlPlatform;
 use OC\Repair\Collation;
 use OCP\IDBConnection;
@@ -41,7 +40,7 @@ class RepairCollationTest extends TestCase {
 	private $repair;
 
 	/**
-	 * @var Connection|IDBConnection
+	 * @var IDBConnection
 	 */
 	private $connection;
 
@@ -61,7 +60,7 @@ class RepairCollationTest extends TestCase {
 	protected function setUp(): void {
 		parent::setUp();
 
-		$this->connection = \OC::$server->getDatabaseConnection();
+		$this->connection = \OC::$server->get(IDBConnection::class);
 		$this->logger = $this->createMock(ILogger::class);
 		$this->config = \OC::$server->getConfig();
 		if (!$this->connection->getDatabasePlatform() instanceof MySqlPlatform) {
@@ -70,13 +69,13 @@ class RepairCollationTest extends TestCase {
 
 		$dbPrefix = $this->config->getSystemValue("dbtableprefix");
 		$this->tableName = $this->getUniqueID($dbPrefix . "_collation_test");
-		$this->connection->exec("CREATE TABLE $this->tableName(text VARCHAR(16)) COLLATE utf8_unicode_ci");
+		$this->connection->prepare("CREATE TABLE $this->tableName(text VARCHAR(16)) COLLATE utf8_unicode_ci")->execute();
 
 		$this->repair = new TestCollationRepair($this->config, $this->logger, $this->connection, false);
 	}
 
 	protected function tearDown(): void {
-		$this->connection->getSchemaManager()->dropTable($this->tableName);
+		$this->connection->getInner()->getSchemaManager()->dropTable($this->tableName);
 		parent::tearDown();
 	}
 
diff --git a/tests/lib/Repair/RepairSqliteAutoincrementTest.php b/tests/lib/Repair/RepairSqliteAutoincrementTest.php
index 9db0d5630aa..c03eb12b894 100644
--- a/tests/lib/Repair/RepairSqliteAutoincrementTest.php
+++ b/tests/lib/Repair/RepairSqliteAutoincrementTest.php
@@ -8,6 +8,7 @@
 
 namespace Test\Repair;
 
+use OC\DB\Connection;
 use OCP\Migration\IOutput;
 
 /**
@@ -23,7 +24,7 @@ class RepairSqliteAutoincrementTest extends \Test\TestCase {
 	private $repair;
 
 	/**
-	 * @var \Doctrine\DBAL\Connection
+	 * @var Connection
 	 */
 	private $connection;
 
@@ -40,7 +41,7 @@ class RepairSqliteAutoincrementTest extends \Test\TestCase {
 	protected function setUp(): void {
 		parent::setUp();
 
-		$this->connection = \OC::$server->getDatabaseConnection();
+		$this->connection = \OC::$server->get(\OC\DB\Connection::class);
 		$this->config = \OC::$server->getConfig();
 		if (!$this->connection->getDatabasePlatform() instanceof \Doctrine\DBAL\Platforms\SqlitePlatform) {
 			$this->markTestSkipped("Test only relevant on Sqlite");
@@ -48,7 +49,7 @@ class RepairSqliteAutoincrementTest extends \Test\TestCase {
 
 		$dbPrefix = $this->config->getSystemValue('dbtableprefix', 'oc_');
 		$this->tableName = $this->getUniqueID($dbPrefix . 'autoinc_test');
-		$this->connection->exec('CREATE TABLE ' . $this->tableName . '("someid" INTEGER NOT NULL, "text" VARCHAR(16), PRIMARY KEY("someid"))');
+		$this->connection->prepare('CREATE TABLE ' . $this->tableName . '("someid" INTEGER NOT NULL, "text" VARCHAR(16), PRIMARY KEY("someid"))')->execute();
 
 		$this->repair = new \OC\Repair\SqliteAutoincrement($this->connection);
 	}
diff --git a/tests/lib/Security/CredentialsManagerTest.php b/tests/lib/Security/CredentialsManagerTest.php
index 9c1a0cb9291..3ce80227f44 100644
--- a/tests/lib/Security/CredentialsManagerTest.php
+++ b/tests/lib/Security/CredentialsManagerTest.php
@@ -21,6 +21,7 @@
 
 namespace Test\Security;
 
+use OC\DB\ConnectionAdapter;
 use OC\Security\CredentialsManager;
 use OC\SystemConfig;
 use OCP\IDBConnection;
@@ -38,13 +39,19 @@ class CredentialsManagerTest extends \Test\TestCase {
 	/** @var IDBConnection */
 	protected $dbConnection;
 
+	/** @var ConnectionAdapter */
+	protected $dbConnectionAdapter;
+
 	/** @var CredentialsManager */
 	protected $manager;
 
 	protected function setUp(): void {
 		parent::setUp();
 		$this->crypto = $this->createMock(ICrypto::class);
-		$this->dbConnection = $this->getMockBuilder('\OC\DB\Connection')
+		$this->dbConnection = $this->getMockBuilder(IDBConnection::class)
+			->disableOriginalConstructor()
+			->getMock();
+		$this->dbConnectionAdapter = $this->getMockBuilder(ConnectionAdapter::class)
 			->disableOriginalConstructor()
 			->getMock();
 		$this->manager = new CredentialsManager($this->crypto, $this->dbConnection);
@@ -91,9 +98,9 @@ class CredentialsManagerTest extends \Test\TestCase {
 			->with('baz')
 			->willReturn(json_encode('bar'));
 
-		$qb = $this->getMockBuilder('\OC\DB\QueryBuilder\QueryBuilder')
+		$qb = $this->getMockBuilder(\OC\DB\QueryBuilder\QueryBuilder::class)
 			->setConstructorArgs([
-				$this->dbConnection,
+				$this->dbConnectionAdapter,
 				$this->createMock(SystemConfig::class),
 				$this->createMock(ILogger::class),
 			])
@@ -103,7 +110,7 @@ class CredentialsManagerTest extends \Test\TestCase {
 			->method('execute')
 			->willReturn($this->getQueryResult(['credentials' => 'baz']));
 
-		$this->dbConnection->expects($this->once())
+		$this->dbConnectionAdapter->expects($this->once())
 			->method('getQueryBuilder')
 			->willReturn($qb);
 
diff --git a/tests/lib/ServerTest.php b/tests/lib/ServerTest.php
index 1054c4195b2..8df39ca7cc9 100644
--- a/tests/lib/ServerTest.php
+++ b/tests/lib/ServerTest.php
@@ -72,7 +72,7 @@ class ServerTest extends \Test\TestCase {
 			['CryptoWrapper', '\OC\Session\CryptoWrapper'],
 			['CsrfTokenManager', '\OC\Security\CSRF\CsrfTokenManager'],
 
-			['DatabaseConnection', '\OC\DB\Connection'],
+			['DatabaseConnection', '\OC\DB\ConnectionAdapter'],
 			['DatabaseConnection', '\OCP\IDBConnection'],
 			['DateTimeFormatter', '\OC\DateTimeFormatter'],
 			['DateTimeFormatter', '\OCP\IDateTimeFormatter'],
diff --git a/tests/lib/TestCase.php b/tests/lib/TestCase.php
index 69cf2a39792..6cadf9693c3 100644
--- a/tests/lib/TestCase.php
+++ b/tests/lib/TestCase.php
@@ -261,7 +261,12 @@ abstract class TestCase extends \PHPUnit\Framework\TestCase {
 		}
 		$dataDir = \OC::$server->getConfig()->getSystemValue('datadirectory', \OC::$SERVERROOT . '/data-autotest');
 		if (self::$wasDatabaseAllowed && \OC::$server->getDatabaseConnection()) {
-			$queryBuilder = \OC::$server->getDatabaseConnection()->getQueryBuilder();
+			$db = \OC::$server->getDatabaseConnection();
+			if ($db->inTransaction()) {
+				$db->rollBack();
+				throw new \Exception('There was a transaction still in progress and needed to be rolled back. Please fix this in your test.');
+			}
+			$queryBuilder = $db->getQueryBuilder();
 
 			self::tearDownAfterClassCleanShares($queryBuilder);
 			self::tearDownAfterClassCleanStorages($queryBuilder);