组 通过选择固定的行返回，而忽略最上面的行 SQL Server

Question

我有一个表。

Customer           Purchase
John                 5
John                 8
John                 3
John                 1  
Sally                3
Sally                5
Sally                2

我想为每个客户返回两条记录 忽略最上面的购买。

John                  5
John                  3
Sally                 3
Sally                 2 

Answer 1

用 ROW_NUMBER() 窗口功能。

select t.customer, t.purchase
from (
  select *, row_number() over (partition by customer order by purchase desc) rn
  from tablename
) t
where t.rn between 2 and 3