选择条件分组依据的列表 [英] Select List for a Conditional Group By

问题描述

这是我打算编写的SQL查询

Hi,

Here''s a SQL Query I intend to write

SELECT CASE COUNT(*) WHEN 1 THEN ColA ELSE MAX(ColA) END FROM tblMyTable GROUP BY CASE Cond1 WHEN 1 THEN ColB END

这是有条件的.当不应用分组依据时，我需要列A的值.如果将其分组，那么我想获得列A的最大值.


如预期的那样，这在选择列表中显示错误

It''s a conditional group by. When the group by is not applied, I need the column A''s value. And If it''s grouped then I want to the Max of Column A''s values.


As expected this shows the error

invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.

有什么建议吗?

Any suggestions?

推荐答案

我认为您将不得不使用动态SQL

I think you will have to use dynamic SQL

declare @strSql nvarchar(100)
declare @count int
select @count = COUNT(*) from tblMyTable where ID = 1
set @strSql ='select ' +
                case @count when 1 then ' ColA '
                else 'MAX(ColA)' end
+ 'from tblMyTable '
+ 'group by ' + case @count when 1 then  ' ColA '
                else ' ColB ' end

sp_executesql @strSql

这篇关于选择条件分组依据的列表的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！