20190422 T-SQL 触发器

-- 1 数据库服务

-- 2 触发器

CREATE TRIGGER no_insert
on xs
AFTER INSERT
AS
BEGIN
RAISERROR('XS不让插入数据',1,1);
ROLLBACK TRANSACTION
END

SELECT *
FROM XS WHERE 学号='14311011'

INSERT INTO xs(学号,姓名,总学分)
values('14311011','soar1','20')

EXEC Sp_helptext no_insert -- sys.sp_ -- 触发器的查看内容

-- 触发器的启用和禁用

-- 删除

DROP TRIGGER no_insert

--重命名
EXEC sp_rename no_insert,new_insert;

-- 禁用和启用触发器，语句

ALTER TABLE XS DISABLE TRIGGER new_insert

ALTER TABLE XS ENABLE TRIGGER new_insert

-- INSERT

-- DELETE

SELECT *
FROM XS WHERE 学号='14311011'

--

DELETE FROM XS
WHERE 学号='14311011'; -- 1

CREATE TRIGGER xs_del
ON XS
AFTER DELETE
AS
BEGIN
SELECT 学号 AS '被删除的学生',姓名 FROM deleted
END

-- UPDATE 更新 ，更新为 test

SELECT *
FROM XS WHERE 学号='14311011'

UPDATE XS SET 姓名='soar'
WHERE 学号='14311011'

SELECT LEN('soar.pang')

--
CREATE TRIGGER XS_UPDATE
ON XS
AFTER UPDATE
AS
BEGIN
SELECT 姓名 as '更改后',学号 FROM inserted;
SELECT 姓名 as '更新前',学号 FROM deleted;
END

-- 真的数据库的触发器

CREATE TRIGGER safty
ON DATABASE -- ALL SERVER 表
FOR DROP_TABLE,ALTER_TABLE -- AFTER
AS
BEGIN
PRINT '当前数据库禁止更新删除动作' --并更
ROLLBACK TRANSACTION
END

DROP TABLE Test_2019_02;

-- 表级、服务器、数据库级别

-- 级联
CREATE TRIGGER trigdel
ON XS
AFTER DELETE
AS
BEGIN
DELETE XK WHERE 学号=(SELECT 学号 from deleted)
END

SELECT * FROM XS where 学号='14311002'
SELECT * from xk where 学号='14311002' -- inner join
-- where

DELETE XS WHERE 学号='14311002'

-- 索引

-- 第一个索引 位置