Sql触发器
use ITweb
go
if exists(select * from sysobjects where name='bank') --判断是否存在这个表
drop table bank --存在的话删除
if exists(select * from sysobjects where name='transInfo')--判断是否存在这个表
drop table transInfo --存在的话删除
go
create table bank
(
customerName char(8) not null, --顾客姓名
cardID char(10) not null, --卡号
currentMoney money not null --当前余额
)
create table transInfo
(
cardID char(10) not null, --卡号
transType char(4) not null, --交易类型
transMoney money not null, --交易金额
transDate datetime not null --交易日期
)
go
alter table bank
add constraint CK_currentMoney check(currentMoney>=1)
alter table transInfo
add constraint DF_transDate default(getDate()) for transDate
go
insert into bank values('张三', '1001 0001', 1000)
insert into bank values('李四', '1001 0002', 1)
insert into transInfo(cardID,transType,transMoney) values('1001 0001','支取',200)
select * from bank
select * from transInfo
go
/*---------------- 练习一 -------------------*/
use ITweb
go
if exists(select name from sysobjects where name='trig_transInfo')
drop trigger trig_transInfo
go
create trigger trig_transInfo
on transInfo
for insert
as
declare @cardID char(10),@transType char(4),@transMoney money,@balance int
select @cardID=cardID,@transType=transType,@transMoney=transMoney from inserted
select @balance=currentMoney from bank where cardID=@cardID
if (@transType='支取')
if (@balance<=@transMoney+1)
raiserror ('您的余额不足!帐上余额 %d 元',16,1,@balance)
else
update bank set currentMoney=currentMoney-@transMoney where cardID=@cardID
else
update bank set currentMoney=currentMoney+@transMoney where cardID=@cardID
if (@@error<>0)
begin
print '交易失败!'
rollback transaction
end
else
print '交易成功!'
select @balance=currentMoney from bank where cardID=@cardID
print '卡号:'+@cardID+' 余额:'+convert(varchar(15),@balance)+' 元'
print ''
go
-- 测试
set nocount on
delete from transInfo
print '------ 交易前的数据 -------'
select * from bank
select * from transInfo
print '测试张三取钱 1500 元'
insert into transInfo(cardID,transType,transMoney)
values('1001 0001','支取',1500)
go
print '测试李四存钱 2000 元'
insert into transInfo(cardID,transType,transMoney)
values('1001 0002','存入',2000)
print '------ 交易后的数据 -------'
select * from bank
select * from transInfo
go
Create Trigger trUserFriendGroupMember
On UserFriendGroupMember --在Student表中创建触发器
for Insert --为什么事件触发
As --事件触发后所要做的事情
declare @UserFriendGroupMemberID uniqueidentifier,@UserFriendGroupID uniqueidentifier,@FriendUserID uniqueidentifier
select @UserFriendGroupMemberID=UserFriendGroupMemberID,@UserFriendGroupID=UserFriendGroupID,@FriendUserID=FriendUserID from inserted
update UserFriendGroup set UserFriendGroupCount=UserFriendGroupCount+1 where UserFriendGroupID=@UserFriendGroupID
go
触发器执行时用到的两个特殊表:deleted ,inserted
deleted 和inserted 可以说是一种特殊的临时表,是在进行激活触发器时由系统自动生成的,其结构与触发器作用的表结构是一
样的,只是存放 的数据有差异。
提示 不建议使用 不好维护 找不到