Trigger
Step : Open the selected ' database ' and turn on ' programmability ' to find the ' database trigger '.
is a stored procedure, but does not execute through EXEC calls!
The execution is triggered by adding or removing changes to the statement !
When you have a primary foreign key association, you can modify the associated information
(When you have a primary foreign key association, you can delete the primary key before deleting the foreign key)
CREATE TABLE New
(Code int,
Shu int)
Go
INSERT into new values (
INSERT into new values (2,3)
INSERT into new values (3,4)
INSERT into new values (4,5)
INSERT into new values (5,6)
Select *from New
drop table New
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Create Trigger Tr_new_delete-- Create and name a trigger
on New-- Acting on New Table
for Delete--delete/insert/update-- Execute DELETE statement first , then insert the statement
As
INSERT into new values (11,11)-occupies the location of the deleted data
INSERT into new values (3,4)--the location of the newly inserted data
Go – to this, the trigger is complete.
Delete from new where code=3
--trigger statement, can only be deleted and modified
Select *from New
For/after run go before running as
--Go Delete code=3 first, then as add code=11,code=3
--Drop Trigger Tr_new_delete
--------------------------------------------------
Create Trigger Tr_new_delete
On new
Instead of delete
As
INSERT into new values (11,11)
Go
Delete from new where code=2
SELECT * FROM New
--Do not execute DELETE statement at this time, only execute INSERT statement!
instead of Run only as the statement
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Alter TRIGGER DONGTAICHUFA
On teacher
Instead of delete
As
Begin
DECLARE @Tno varchar (20)
Set @Tno = (select Tno from deleted)
--deleted represents a virtual table ( Go behind the Delete statement)
Update teacher set Tname= ' recursion ' where [email protected]
End
Go
Delete from teacher where tno= ' 856 '
Select *from Teacher
---------------------------------------------
-- a trigger can handle a view, (Purpose: 1. Backup 2 When deleting data . operation View, when there is a primary foreign key association)
Create Trigger INSERTTT
On teacher
For insert
As
DECLARE @Tno varchar (19)
Set @Tno = (select Tno from inserted)
Update teacher set tsex= ' male ' where [email protected]-- Modify Table Contents
Go
Insert INTO teacher values
(' 789 ', ' Set ', ' Female ', ' 1990-09-09 ', ' Professor ', ' Biology Department ')
Select *from Teacher
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Alter table teacher Disable trigger all--( or trigger name ) Disable all
ALTER TABLE teacher enable trigger all--(or trigger name) all
Triggers in the database