DECLARE
	UPD NUMBER(20);
	B NUMBER(10);
BEGIN
--***************FOR UPDATE ALERT (NOT WORKING THIS BLOCK)**********************************

  SELECT SALE.BILL_NO INTO B FROM SALE WHERE SALE.BILL_NO=:SALE.BILL_NO;
	
	IF 
		:SALE.BILL_NO=B THEN
		UPD:=SHOW_ALERT('UPDATE');
		IF UPD=ALERT_Button1 THEN
	
			--SYSTEM.MESSAGE_LEVEL:=5;
			COMMIT_FORM;
			--SYSTEM.MESSAGE_LEVEL:=25;
		END IF;
--***************FOR UPDATE ALERT (WORKING ACCURATE)**********************************
	ELSIF 
                      :SALE.PRICE IS NULL THEN
                       MESSAGE ('NOT INSERT BECAUSE OF EMPTY FIELD');
                       MESSAGE ('NOT INSERT BECAUSE OF EMPTY FIELD');
        ELSE
                      COMMIT_FORM;
END IF;
END;