CREATE rule mavue_upadate AS ON UPDATE TO une_vue DO INSTEAD SELECT updatemavue_trigger(NEW)

CREATE OR REPLACE FUNCTION updatemavue_trigger(enreg record) RETURNS void AS $$
DECLARE
	un_enreg enreg%ROWTYPE;
	msql varchar :='';
	i integer default 0;
BEGIN
	SELECT * INTO un_enreg FROM matable WHERE id=enreg.id;
	IF FOUND THEN
		
		IF un_enreg.nom <> enreg.nom THEN
			msql := 'nom = ' || enreg.nom;
			i:=1;
		END IF;
		
		IF un_enreg.prenom <> enreg.prenom AND i<>0 THEN
			msql := msql || ' AND prenom=' || enreg.prenom;
		ELSE
			msql := 'prenom=' || enreg.prenom;
			i:=1;
		END IF;
						
		IF i<>0 THEN
			EXECUTE 'UPDATE matable SET ' || msql;
		END IF;
		
	else
		RAISE EXCEPTION 'Update impossible';
	END IF;
END;
$$
LANGUAGE plpgsql;