如何将两个相似的分组结果集合并为一个？答案

【问题标题】：How can I combine two similar grouped result sets into one?如何将两个相似的分组结果集合并为一个？
【发布时间】：2012-11-27 19:28:47
【问题描述】：

我有几个 SQL Server 2012 查询正在工作，但不知道如何将它们组合成一个结果集。我希望将 [Total Claims] 和 [Reversed Claims] 视为同一结果集中的相邻列。这可能吗？

select [Date], DATENAME(weekday, [Date]) as [Day], [Total Claims]
from (Select [Date], count(*) as [Total claims] from ClaimHistoryView group by [Date] )
as CountByDay
order by [Date] desc

select [Date], DATENAME(weekday, [Date]) as [Day], [Reversed Claims]
from (Select [Date], count(*) as [Reversed Claims] from ClaimHistoryView where status = 2 group by [Date] ) as CountByDay
order by [Date] desc

【问题讨论】：

标签： sql sql-server-2012

【解决方案1】：

诀窍是使用“union all”将这两个查询与另一列结合起来，该列指示数据的来源，然后进行选择性透视。唔。复杂的解释（对不起，德语）

这应该可以解决问题

select [Date], 
       DATENAME(weekday, [Date]) as [Day], 
       sum(case when Source = 1 then value else 0 end) as [Total Claims],
       sum(case when Source = 2 then value else 0 end) as [Reversed Claims]
from
(
  select 
        1 as source, 
        [Date], 
        count(*) as value 
  from  ClaimHistoryView 
  group by [Date]
union all
  select 
        2 as source,
        [Date],  
        count(*) as value 
  from  ClaimHistoryView 
  where status = 2 
  group by [Date]
) as CountByDay 
Group by [Date]
order by [Date] desc

【讨论】：

非常感谢。请注意，“2 作为来源”之后需要一个逗号。