Add constraint to stop fast webhooks from creating 2 events with… (CoderDojo#169)

* Add constraint to stop very fast webhooks from creating 2 events with the same eb_id

* Fix condition of error handling
catchall bcause of lazyness

Author: Wardormeur

scripts/database/pg/migrations/020.do.add-constraint-unique-eventbrite-event-id.sql

@@ -0,0 +1,9 @@
+DO $$
+  BEGIN
+    BEGIN
+        ALTER TABLE cd_events ADD UNIQUE (eventbrite_id);
+    EXCEPTION
+        WHEN OTHERS THEN RAISE NOTICE 'constraint eventbrite_id already exists in cd_events.';
+    END;
+  END;
+$$