/* Insert - Add New value */
CREATE OR REPLACE TRIGGER trg_actualizarpedido1
AFTER INSERT ON LINEAS
FOR EACH ROW
BEGIN
    UPDATE PEDIDOS
    SET TOTAL = TOTAL + :NEW.IMPORTE
    WHERE NUMPEDIDO = :NEW.NUMPEDIDO ;
END;

/* Update - Subtract the Old value, Add New value */
CREATE OR REPLACE TRIGGER trg_actualizarpedido2
AFTER UPDATE ON LINEAS
FOR EACH ROW
BEGIN
    UPDATE PEDIDOS
    SET TOTAL = TOTAL - :OLD.IMPORTE + :NEW.IMPORTE
    WHERE NUMPEDIDO = :NEW.NUMPEDIDO ;
END;

/* Delete - Subtract the Old value */
CREATE OR REPLACE TRIGGER trg_actualizarpedido3
AFTER DELETE ON LINEAS
FOR EACH ROW
BEGIN
    UPDATE PEDIDOS
    SET TOTAL = TOTAL - :OLD.IMPORTE
    WHERE NUMPEDIDO = :OLD.NUMPEDIDO ;
END;