Question

我有一个CustomerMaster表，其中有一个名为AccountBalance的列。每个客户（由CustomerMaster中的CustomerId唯一标识）可以在ClientTransaction表中具有0,1或多个事务，该表具有名为Amount的列（指示事务量）。我想在ClientTransaction表上为INSERT，UPDATE和DELETE创建一个触发器来维护AccountBalance。我尝试过定义下面的触发器;当我只删除一行时，它会正确更新AccountBalance;但是，当我执行DELETE ClientTransaction删除所有记录时，它不起作用。有什么想法吗？

CREATE TRIGGER [dbo].[ClientAccountBalanceUpdate]
   ON  [dbo].[ClientTransaction]
   FOR INSERT,DELETE,UPDATE
AS  
BEGIN
    SET NOCOUNT ON;

    if not exists (select 1 from Inserted) -- Delete trigger
        update CustomerMaster set AccountBalance = AccountBalance - D.Amount from CustomerMaster inner join Deleted D on CustomerMaster.CustomerId = D.CustomerId 

    if not exists (select 1 from Deleted) -- Insert Trigger
        update CustomerMaster set AccountBalance = AccountBalance + I.Amount from CustomerMaster inner join Inserted I on CustomerMaster.CustomerId = I.CustomerId

    if  exists (select 1 from Deleted) and exists (select 1 from Inserted) -- Update trigger
        update CustomerMaster set AccountBalance = AccountBalance - D.Amount + I.Amount from CustomerMaster inner join Inserted I on CustomerMaster.CustomerId = I.CustomerId inner join Deleted D on CustomerMaster.CustomerId = D.CustomerId

END

Answer 1

正如评论中所述，您的问题是您的代码仅在有一个交易时才有效。下面是您的代码在插入中处理多行的示例。

If Not Exists (Select 1 From Deleted) -- Insert Trigger
    Update CustomerMaster 
    Set AccountBalance = AccountBalance + 
        (
        Select Sum(I.Amount)
        From Inserted I 
        Where CustomerMaster.CustomerId = I.CustomerId
        )
    From CustomerMaster

Answer 2

您的触发器仅触发一次（插入，更新或删除第一行时）。

如果您insert，delete或update超过1行，则下次不会触发您的触发器，除非满足下2个条件（按给定顺序）：< / p>

所有队列（已插入，已删除和已更新）已清空
插入，删除和更新后全部为空，插入，删除或更新另一行。

在SQL Server 2012中触发以更新帐户余额

2 个答案: