| 2 | | |
| 3 | | <syntaxhighlight lang="sql"> |
| 4 | | CREATE OR REPLACE FUNCTION trg_prevent_double_booking() |
| 5 | | RETURNS TRIGGER |
| 6 | | AS $$ |
| 7 | | BEGIN |
| 8 | | IF NEW.booking_status IN ('PENDING','CONFIRMED') THEN |
| 9 | | IF EXISTS ( |
| 10 | | SELECT 1 |
| 11 | | FROM bookings b |
| 12 | | WHERE b.room_id = NEW.room_id |
| 13 | | AND b.booking_status IN ('PENDING','CONFIRMED') |
| 14 | | AND daterange(b.check_in_date, b.check_out_date, '[)') |
| 15 | | && daterange(NEW.check_in_date, NEW.check_out_date, '[)') |
| 16 | | ) THEN |
| 17 | | RAISE EXCEPTION 'Room % is already booked', NEW.room_id; |
| 18 | | END IF; |
| 19 | | END IF; |
| 20 | | |
| 21 | | RETURN NEW; |
| 22 | | END; |
| 23 | | $$ LANGUAGE plpgsql; |
| 24 | | |
| 25 | | CREATE OR REPLACE TRIGGER prevent_double_booking |
| 26 | | BEFORE INSERT ON bookings |
| 27 | | FOR EACH ROW |
| 28 | | EXECUTE FUNCTION trg_prevent_double_booking(); |
| 29 | | </syntaxhighlight> |
| | 2 | <pre> |
| | 3 | CREATE OR REPLACE FUNCTION ... |
| | 4 | ... |
| | 5 | </pre> |
