Rank 获取排序的序号

Select *,RANK() over (partition by 分组列名 order by 排序列名) as rn from [Table]

例如：获取按…分组的按…排序的每组的前2条记录

select Table1.* from

(

select *,RANK()
over (partition by a.列1,a.列2, order by a.列3) as rn
from Table1

) as Table2 

where rn < 3