1 files changed, 23 insertions, 0 deletions
diff --git a/lib/gitlab/sql/intersect.rb b/lib/gitlab/sql/intersect.rb
new file mode 100644
index 00000000000..c661db3d4c5
--- /dev/null
+++ b/lib/gitlab/sql/intersect.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module SQL
+    # Class for building SQL INTERSECT statements.
+    #
+    # ORDER BYs are dropped from the relations as the final sort order is not
+    # guaranteed any way.
+    #
+    # Example usage:
+    #
+    #     hierarchies = [group1.self_and_hierarchy, group2.self_and_hierarchy]
+    #     intersect   = Gitlab::SQL::Intersect.new(hierarchies)
+    #     sql         = intersect.to_sql
+    #
+    #     Project.where("id IN (#{sql})")
+    class Intersect < SetOperator
+      def self.operator_keyword
+        'INTERSECT'
+      end
+    end
+  end
+end