PDDA-594 Adding constraint on xhb_sitting to prevent duplicates

Author: gittinsl

src/main/resources/database/scripts/V1_5_3__pdda-amend-constraints.sql

@@ -0,0 +1,6 @@
+ALTER TABLE xhb_sitting
+DROP CONSTRAINT IF EXISTS sitting_unique;
+
+ALTER TABLE xhb_sitting
+ADD CONSTRAINT sitting_unique
+UNIQUE (sitting_time, court_room_id, court_site_id);