CONFLICTS_VIEW_SQL = <<EOS CREATE VIEW "conflicts" AS SELECT "left"."talk_id" AS left, "right"."talk_id" AS right, COUNT(*) AS "conflicts" FROM "selected_talks" AS "left" INNER JOIN "selected_talks" AS "right" ON "left"."talk_preference_id" = "right"."talk_preference_id" WHERE "left"."talk_id" != "right"."talk_id" GROUP BY "left"."talk_id", "right"."talk_id"; EOS class AddConflictsView < ActiveRecord::Migration[5.0] def up execute CONFLICTS_VIEW_SQL end def down execute 'DROP VIEW "conflicts"' end end