====== TP4 ======

1b
<code sql>
CREATE OR REPLACE TRIGGER TR1b
AFTER DELETE ON Artiste
FOR EACH ROW
BEGIN
UPDATE Album SET Artiste = NULL WHERE Artiste = :old.nom;
END;
</code>

1c
<code sql>
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;
</code>