TP4

1b

CREATE OR REPLACE TRIGGER TR1b
AFTER DELETE ON Artiste
FOR EACH ROW
BEGIN
UPDATE Album SET Artiste = NULL WHERE Artiste = :OLD.nom;
END;

1c

CREATE OR REPLACE TRIGGER TR1c
AFTER DELETE ON artiste
FOR EACH ROW
BEGIN
DELETE album WHERE artiste = :OLD.nom;
END;
 
CREATE OR REPLACE TRIGGER T1c2
AFTER DELETE ON album
FOR EACH ROW
BEGIN
DELETE chanson WHERE album = :OLD.titre;
END;