根据交易金额确定会员是否升级为VIP

--建立用户表
--username是主键,金额,和成为会员的日期
CREATE TABLE tbOrder(username Varchar(100) PRIMARY KEY,sumprice Money,IsLeaguer Datetime)
go

--建立触发器
--名称:tr_tbOrder
--功能:当有用户的金额>=500时,自动确定他何时会成为会员,存放到IsLeaguer中
CREATE TRIGGER tr_tbOrder
ON tbOrder
FOR INSERT, UPDATE
AS
If UPDATE(sumprice)
BEGIN
  declare @sStr Nvarchar(100),@dDate datetime
  select @dDate = dateadd(day,15,getdate())
  select @sStr = username from inserted
  --更新:通过匹配用户名,金额和是否已经成为会员来确定更新
  exec('update tbOrder set IsLeaguer = ''' + @dDate + ''' where username = ''' + @sStr + ''' and sumprice >= 500 and IsLeaguer is NULL')
END
go

--放入测试数据
insert into tbOrder(username,sumprice) select 'aa',500
insert into tbOrder(username,sumprice) select 'bb',600
insert into tbOrder(username,sumprice) select 'cc',400
go

--演示,IsLeaguer字段的日期<=当前时间的就是已经成为会员的
select * from tbOrder where IsLeaguer <= getdate()
go

--drop table tbOrder
--drop trigger tr_tbOrder