Row_Number() 分组排序

  SELECT  a.id          ,a.cnname         ,b.personid                           ,Row_number() OVER(partition BY personid ORDER BY releasetime DESC) num         ,releasetime                  from   ent_movie a           LEFT JOIN ent_movie_relate_person b ON a.id = b.movieid                                   WHERE  a.typeid=1 and a.cnName is not null and a.cnName!=''          AND b.professionid = 1         and a.releaseTime>=DATEADD(YY,-3,GETDATE()) and  a.releaseTime<=GETDATE()

语法形式：ROW_NUMBER() OVER(PARTITION BY COL1 ORDER BY COL2) 

解释：根据COL1分组，在分组内部根据 COL2排序，而此函数计算的值就表示每组内部排序后的顺序编号（组内连续的唯一的) 

参考学习：http://www.jb51.net/article/29162.htm