对于TSQL插入/更新触发器，可以插入和删除都为空吗？(For a TSQL insert/update trigger, can inserted and deleted both be empty?)

 我一直在使用TSQL触发器，假设insert表总是包含插入或更新的记录，而删除的表总是包含更新记录（我忽略删除）。 
 
 这是相关的MSDN文章： 
 
 http://msdn.microsoft.com/en-us/library/ms191300.aspx 
 
 但是，我遇到插入和删除都为空的情况。 这是我一直在使用的测试触发器。 
 
CREATE TRIGGER [dbo].[InsertUpdateTest] ON [dbo].[Test] 
AFTER INSERT, UPDATE 
AS
    DECLARE @countInserted INT
    DECLARE @countDelete INT

    SET @countInsert = (SELECT COUNT(*) FROM INSERTED)
    SET @countDeleted = (SELECT COUNT(*) FROM DELETED)

    IF (@countInserted = 0 AND @countDelete = 0)
    BEGIN
        print 'Inserted and deleted are both empty'
    END
 
 在什么条件下会发生这种情况？ 

I have been using a TSQL trigger under the assumption that the inserted table always contains records for an insert or update and the deleted table always contains records for updates (I am ignoring deletes).
 
Here is the related MSDN article:
 
http://msdn.microsoft.com/en-us/library/ms191300.aspx
 
However, I have encountered situations where both inserted and deleted are empty. Here is a test trigger I have been using.
 
CREATE TRIGGER [dbo].[InsertUpdateTest] ON [dbo].[Test] 
AFTER INSERT, UPDATE 
AS
    DECLARE @countInserted INT
    DECLARE @countDelete INT

    SET @countInsert = (SELECT COUNT(*) FROM INSERTED)
    SET @countDeleted = (SELECT COUNT(*) FROM DELETED)

    IF (@countInserted = 0 AND @countDelete = 0)
    BEGIN
        print 'Inserted and deleted are both empty'
    END
 
Under what conditions does this occur?

原文：https://stackoverflow.com/questions/11791294