Question

我正在尝试在数据库中创建触发器。

我有两个表，一个用于客户信息，一个用于客户订单。我想创建一个FOR DELETE触发器，以便在从订单表中删除订单时，应该从客户帐户中减少该订单的费用。

首先，我创建一个AFTER INSERT触发器，效果很好！

代码如下：

ALTER TRIGGER [dbo].[set_customer_debt]
ON [dbo].[orders]
AFTER INSERT
AS 
BEGIN
    UPDATE customer
    SET debt = debt + (SELECT cost FROM orders
                       INNER JOIN services ON services.service# = orders.service#
                       WHERE orders.order# IN (SELECT order# FROM inserted))
    WHERE customer# IN (SELECT customer# FROM inserted)
END

然后，我将其复制并更改为FOR DELETE，但对于债务它只返回NULL：

ALTER TRIGGER [dbo].[delete_customer_debt]
ON [dbo].[orders]
FOR DELETE
AS 
BEGIN
    UPDATE customer
    SET debt = debt - (SELECT cost FROM orders
                       INNER JOIN services ON services.service# = orders.service#
                       WHERE orders.order# IN (SELECT order# FROM deleted))
    WHERE customer# IN (SELECT customer# FROM deleted)
END

问题出在哪里？

SQL Server ON DELETE触发器无法按预期工作

0 个答案: