SQL Server 2008 中的“交叉表”查询

Question

使用 SQL Server 2008，希望查询一个表，但要查找特定的输出。当前表，名为 fmCalendar：

>Date       Calendar    Days
>12/30/2014 Canada      1
>12/30/2014 Europe      1
>12/30/2014 UK          1
>12/30/2014 US          1
>12/29/2014 Canada      2
>12/29/2014 Europe      2
>12/29/2014 UK          3
>12/29/2014 US          3
>...

我希望输出如下所示：

>Date       Canada  Europe  UK  US
>12/30/2014 1       1       1   1
>12/29/2014 2       2       3   3
>...

我该怎么做？提前致谢

Answer 1

我会这样查询

select
  Date,
  Sum(case when Calendar = 'Canada' then Days else 0 end) as Canada,
  Sum(case when Calendar = 'Europe' then Days else 0 end) as Europe,
  Sum(case when Calendar = 'UK' then Days else 0 end) as UK,
  Sum(case when Calendar = 'US' then Days else 0 end) as Us,
  Sum(case when Calendar not in ('Canada','Europe','UK','US') then Days else 0 end) 
  as Other
from
  MyTable
group by
   Date

Answer 2

你可以做一个PIVOT:

SELECT *
FROM fmCalendar AS T
PIVOT(SUM([days]) FOR Calendar IN ([Canada],[Europe],[UK],[US])) AS P

Here is an sqlfiddle 带有演示。结果是：

╔═══════════════════╦════════╦════════╦════╦════╗
║       DATE        ║ CANADA ║ EUROPE ║ UK ║ US ║
╠═══════════════════╬════════╬════════╬════╬════╣
║ December, 29 2014 ║      2 ║      2 ║  3 ║  3 ║
║ December, 30 2014 ║      1 ║      1 ║  1 ║  1 ║
╚═══════════════════╩════════╩════════╩════╩════╝