如何从PHP MySQL中的两个不同表更新表？

Question

我有3张桌子的预订，订单和库存。 在预订中，我有订单（例如2个苹果和一个橘子）。（reservation.confirmation = orders.confirmation）。 当保留.status更改为“已交付”时，我想更新苹果和橙库存.sold

reservation
---------------------------
confirmation | status

EX-10          pending


orders
---------------------------
confirmation  | product    |  qty

EX-10           apple         2
EX-10           orange        1


inventory
---------------------------
id            | nameofproduct | sold

1               apple           -->update to 2
2               orange          -->update to 1

到目前为止，这里是我的代码。

$confirmation = $_POST['confirmation'];
    $status=$_POST['status'];
    mysql_query("UPDATE reservation SET status='$status' WHERE reservation_id='$roomid'");
    if ($status=='Delivered')
{
    mysql_query("UPDATE inventory SET sold = (SELECT qty FROM orders where confirmation='$confirmation') where nameofproduct=(SELECT prduct FROM orders where confirmation='$confirmatioin')");

        }

请帮助进行正确的查询。 谢谢

Answer 1

您听说过TRIGGERS吗？ 请参阅： http ： //www.sitepoint.com/how-to-create-mysql-triggers/

我已经为您提供了想要的东西，但我没有对其进行检查，因此可能有错误，如果您有任何问题，请告诉我。

DELIMITER $$
CREATE TRIGGER inventory
AFTER UPDATE ON reservation FOR EACH ROW
BEGIN
        DECLARE finished INT DEFAULT 0;
        DECLARE product VARCHAR(200); -- SHOULD BE THE SAME TYPE AND LENGTH AS order.product
        DECLARE qty INT;  -- SHOULD BE THE SAME TYPE AND LENGTH AS order.qty
        DECLARE orders_cursor CURSOR FOR SELECT o.product, o.qty FROM orders o WHERE o.confirmation = NEW.confirmation;
        DECLARE CONTINUE HANDLER FOR NOT FOUND SET finished = 1;



        IF (NEW.status = 'delivered') THEN
            open orders_cursor;
            get_orders: LOOP

                FETCH orders_cursor INTO product, qty;

                IF finished = 1 THEN
                    LEAVE get_orders;
                END IF;

                -- UPDATE INVENTORY
                UPDATE inventory i SET i.sold = qty WHERE i.nameofproduct = product;
            END LOOP get_orders;
            close orders_cursor;
        END IF;


END
$$