http://images.cnitblog.com/blog2015/747019/201505/140840417987202.jpgPartition by 和group by 的区别---实例演示（转）" />

主键为ID

select * from [infotops] where Id in (select max(id) from [infotops] group by InfoId) 

----------------------------------------------------- 巩固----------------------------------------------

group by 

http://images.cnitblog.com/blog2015/747019/201505/141851073922278.jpgPartition by 和group by 的区别---实例演示（转）" />

PARTITION BY  看图比较区别

SELECT ROW_NUMBER() OVER ( PARTITION BY Infoid order by id desc) rowNum ,
*
FROM [InfoTops] t1 with(nolock)  ---》

http://images.cnitblog.com/blog2015/747019/201505/141842292517207.jpgPartition by 和group by 的区别---实例演示（转）" />

with infos as
(
SELECT ROW_NUMBER() OVER ( PARTITION BY Infoid order by id desc) rowNum ,
*
FROM [InfoTops] t1 with(nolock)
)
select * from infos where rowNum=1   ---------------》

http://images.cnitblog.com/blog2015/747019/201505/141845234859476.jpgPartition by 和group by 的区别---实例演示（转）" />

http://images.cnitblog.com/blog2015/747019/201505/141846351261125.jpgPartition by 和group by 的区别---实例演示（转）" />