I get the following error when I try to create this trigger in SQLite
create trigger timeslot_check1 after insert on section
for each row
when(new.time_slot_id not in(select time_slot_id
from time_slot))
begin
rollback
end;
ERROR : near "rollback": syntax error:
As shown in the documentation, the only SQL commands allowed in a trigger body are UPDATE, INSERT, DELETE, and SELECT.
To raise an error, you must use the RAISE() function from inside a query:
CREATE TRIGGER timeslot_check1
BEFORE INSERT ON section
FOR EACH ROW
WHEN NEW.time_slot_id NOT IN (SELECT time_slot_id FROM time_slot)
BEGIN
SELECT RAISE(FAIL, "invalid timeslot");
END;
Anyway, this check can be done much easier with a foreign key.
