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
