SELECT MAX的COUNT

Question

我有一张桌子"好".它包含一列app_rate_unit(类型:nvarchar).我的目标是计算表中的每个不同值,让DBMS(MS Server 2005)给我最多的值.

这是我的代码:

SELECT MAX(app_rate_unit) AS MAX_APP
  FROM (SELECT app_rate_unit, COUNT(*) AS co
          FROM dbo.well AS w
         GROUP BY app_rate_unit
        ) AS derivedtbl_1

然而,与它有关的问题是,我的DBMS实际上为我提供了最低的数量.

SideQuestion:如何在计数时过滤外键(在表中)和NOT NULL(在app_rate_unit中)？

Answer 1

select top 1 app_rate_unit, count(*) from dbo.well
group by app_rate_unit
order by count(*) desc