walleyekneel的专栏

declare @Mcode varchar(100)set @mcode='123456789,'SELECT replace(''''+@mcode+'''',',',''',''') AS CODE 结果是（‘123456789’，‘’）

select casewhen thenelseendfrom[表名][color=cyan]例子：[/color]select 姓名,工龄,(case when (工龄>= '35') then '90%'when (工龄>='30' and 工龄='20' and 工龄='10' and 工龄...

1------SELECT *,(SELECT COUNT(DISTINCT Stu_Score) FROM Table_3 WHERE Stu_Score >= a.Stu_Score) as placeFROM Table_3 a ORDER BY place2----select Stu_score,排名=rank() over (order by Stu_Score...

sql server 2005以上版本可以用access不支持declare @a intset @a=2select top (@a) * from [表名]  

create TRIGGER trigg_testON Admin instead of insert as BEGIN insert into Admin(pwd)select pwd from inserted k where not exists(select * from Admin where pwd=k.pwd) END 插入失败判断返回受影响的行数...

Delete Has_Tested Where stu_uid Not In (Select Max(id) as newsid From Has_Tested Group By stu_uid order by newsid)

MySql中随机提取数据库N条记录select * from TableName order by rand() limit NSQLServer中随机提取数据库N条记录select top N * from TableName order by NEWID()Access中随机提取数据库N条记录SELECT top N * FROM TableName O...

     区别： having语句是滴分组后的信息进行过滤，而where语句是对原始数据进行过滤