更新触发问题的更新

Question

我的名字有一个表上的触发器：[OfficeAutomation_Letter]每行更新另一个时间 更新的表我 但是，当更新命令我跑两行 会触发一个错误 我需要解释的过道中的每一行如何发展

我的触发是：

ALTER TRIGGER [dbo].[Letter_UPD] ON [dbo].[OfficeAutomation_Letter] 
FOR UPDATE 
AS 

Declare @LetterID int 
SELECT @LetterID = ID From Inserted 

BEGIN   
    UPDATE OfficeAutomation_TempLetter 
    SET Archived = (Select Archive From Inserted), 
    OriginalNumber = (Select OriginalNumber From Inserted) 
    WHERE LetterID = @LetterID   
END 

更新我的命令是：

update OfficeAutomation_Letter set OriginalNumber=100 where ID in (3,4) 

访问的错误是：

Subquery returned more than 1 value. This is not permitted when 
the subquery follows =, !=, <, <= , >, >= or when the subquery 
is used as an expression. 

Answer 1

触发器每行每声明运行一次，不是一次，inserted和deleted表中的伪包含所有受影响的行。

ALTER TRIGGER [dbo].[Letter_UPD] ON [dbo].[OfficeAutomation_Letter] 
FOR UPDATE 
AS 
    UPDATE otl 
    SET Archived = i.Archive, 
    OriginalNumber = i.OriginalNumber 
    FROM 
     OfficeAutomation_TempLetter otl 
     inner join 
     inserted i 
     on 
      otl.LetterID = i.ID 

所以，在你原来的触发，我们有：？

SELECT @LetterID = ID From Inserted 

这是要分配受影响的行中的一个（谁知道哪一个，的ID - 这是没有定义）

然后

SET Archived = (Select Archive From Inserted), 
OriginalNumber = (Select OriginalNumber From Inserted) 

这是实际您看到错误的原因，因为右侧的选择将返回多行。