CREATE OR REPLACE TRIGGER check_status_orders
BEFORE INSERT ON ORDERS
FOR EACH ROW
BEGIN

FOR ORDER IN (SELECT * FROM ORDERS
                WHERE CUSTOMER_ID = CUSTOMER.CUSTOMER_ID)
    LOOP
        IF (:OLD.STATUS_ID=2 OR :OLD.STATUS_ID=1) THEN
            RAISE_APPLICATION_ERROR(20001, 'ORDER IN PROGRESS');
        END IF;
    END LOOP;
END;
/