Hi, first of all, thank you for your help. Much appreciated. so... i think i forgot to mention: the first versiion of my trigger was this: CREATE TRIGGER 'InsertfehlerPruefung' BEFORE INSERT ON Pruefung BEGIN SELECT CASE WHEN (NEW.theorie = 0 AND (SELECT SUM(dauer) FROM fahrstunde WHERE fahrstunde.schueleremail = NEW.email ) < 180) THEN RAISE(ABORT, 'Nicht genug Fahrstundenminuten') END; END; it was only when it didnt work that i changed it to "not >= 180". Now.. i tried out your version with an emailadress from a student who only has 90minutes and it still gets inserted.