CREATE OR REPLACE TRIGGER VEREFIE_PER
BEFORE INSERT OR UPDATE OF DATEDEBUT,DATEFIN ON Intervenants
FOR EACH ROW
DECLARE
  ROM INTERVENTIONS%ROWTYPE;
BEGIN
IF(INSERTING) THEN
  SELECT * INTO ROM FROM INTERVENTIONS WHERE NUMINTERVENTION =:NEW.NUMINTERVENTION;
  	IF((ROM.DATEDEBINTERV <= :NEW.DATEDEBUT) AND (ROM.DATEFININTERV>= :NEW.DATEFIN ))
  	  THEN DBMS_OUTPUT.PUT_LINE('PERIODE VALIDE');

  	ELSE RAISE_APPLICATION_ERROR(-20658,'PERIODE INVALIDE ');
  	END IF;

ELSE SELECT * INTO ROM FROM INTERVENTIONS WHERE NUMINTERVENTION= :NEW.NUMINTERVENTION;
 	IF((ROM.DATEDEBINTERV <= :NEW.DATEDEBUT) AND (ROM.DATEFININTERV>= :NEW.DATEFIN ))
 	  THEN DBMS_OUTPUT.PUT_LINE('PERIODE VALIDE');

 	ELSE RAISE_APPLICATION_ERROR(-20658,'PERIODE INVALIDE');
 	END IF;
END IF;

END;
/