复杂的TSQL查询（前n个和分组依据合并）

Question

我非常了解TSQL，但是我确实在这里碰壁。

我正在对某些Agent进行一些统计，并且使用group by来构建数据，如下所示：

    select 
    AgentID, 
    [No 14] as answer_option, 
    COUNT(*) as amount_of_answers, 
    CASE 
        WHEN [No 14] = 1 then CONVERT(int, COUNT(*), 1) * 5 
        WHEN [No 14] = 2 then CONVERT(int, COUNT(*), 1) * 4 
        WHEN [No 14] = 3 then CONVERT(int, COUNT(*), 1) * 3 
        WHEN [No 14] = 4 then CONVERT(int, COUNT(*), 1) * 2 
        WHEN [No 14] = 5 then CONVERT(int, COUNT(*), 1) * 1 
        END as combined_weight
from #temptable
where 
[No 14] <> '-'
and AgentID <> '-1'
group by AgentID, [No 14]
order by AgentID, svar

现在一切都很好，直到我被告知数据应该仅基于每个业务代表的最后20个传入行。

代理的最后20行可以这样找到：

select TOP 20 * from #temptable where AgentID = X order by changedDate desc

如何合并这两个查询，这样我只能根据ChangedDate desc将每个座席的前20行放入查询中？

如果只有15行，则应基于这些行。

Answer 1

您可以使用row_number()筛选出每个代理程序的最后20行。 更改：

from #temptable

至：

from    (
        select  row_number() over (partition by AgentID 
                                   order by ChangedDate desc) as rn
        ,       *
        from    #temptable
        ) as SubQueryAlias
where   rn <= 20
        and ...