sqlserver 分组取前n条记录

1.前言。
    这个有两种方法.1是用in,2是用row_number()，可根据情况来用。两种都可以。
2.举例。
方法1:

select  a.* from table1  a  where a.column1 in (select max(column1) from table1 group by a.column2,column3) 

方法2:

with nyr as (
select NYR,QYZX_DM,FXSP_XH,SPBM_DLJ,WBSP_GG,JGLX,JZJG,MAX(SJGX_SJ),
ROW_NUMBER() over (partition by nyr order by nyr) as 'rowno'

from WD_O_T_IC_SPSJ_FX 
where rowno=1
group by NYR,QYZX_DM,FXSP_XH,SPBM_DLJ,WBSP_GG,JGLX,JZJG 
order by NYR,QYZX_DM,FXSP_XH,SPBM_DLJ,WBSP_GG,JGLX,MAX(SJGX_SJ) desc
)
select *
from nyr
where rowno = 1

方法2的补充，带有总数的分页代码

with nyr as (   
select   phone,userid,(counts26+counts27) as times,mobilearea,
ROW_NUMBER() over ( order by userid,phone desc)  as 'rowno'  
  
from a  group  by phone,userid,(counts26+counts27),mobilearea having (counts26+counts27)>0


)   
select *
from nyr   
where rowno >1 and rowno<100000  
union all  (select ''1'',''1'',''1'',isnull((select max(rowno)  from nyr),0))

3.补充说明。
这里主要说下ROW_NUMBER()的用法。
ROW_NUMBER()实现了不用分组，自动在查询结果内部分组，求行号的功能。
如果"ROW_NUMBER() over()" 的括号内有partition by ，那么可以内部分组。如果没有，则是按照1，2,3的顺序依次获得行号。