初学sql,问个简单的trigger问题。

Question

--插入时的TriggerCREATE TRIGGER [author_Insert] ON [dbo].[author] 
FOR  INSERT
AS
Begin
Declare @au_id Nvarchar(50)
select @au_id=au_id from Inserted
Insert titleauthor (au_id) values(@au_id)
End

Answer 1

--删除的Trigger
CREATE TRIGGER [author_Delete] ON [dbo].[author] 
FOR  DELETE
AS
Begin
Declare @au_id Nvarchar(50)
select @au_id=au_id from Deleted
Delete from  titleauthor Where au_id=@au_id
End

Answer 2

--更新的Trigger
CREATE TRIGGER [author_Update] ON [dbo].[author] 
FOR  UPDATE
AS
Begin
Declare @Oldau_id Nvarchar(50)
Declare @Newau_id Nvarchar(50)
select @Oldau_id=au_id from Deleted
select @Newau_id=au_id from Inserted
Update titleauthor Set au_id=@Newau_id Where au_id=@Oldau_id
End

Answer 3

--删除的可以这样改
CREATE TRIGGER [author_Delete] ON [dbo].[author] 
FOR  DELETE
AS
Begin
Delete from  titleauthor Where au_id=(Select au_id from Deleted)
End

Answer 4

--更新的Trigger可以这样改
CREATE TRIGGER [author_Update] ON [dbo].[author] 
FOR  UPDATE
AS
Begin
Update titleauthor Set au_id=(Select au_id from Inserted ) Where au_id=(Select au_id from Deleted )
End