我有这样的桌子...

LEVEL        Action         Date             User
--------------------------------------------------
1            Approve        01/01/2013       User1
2            Approve        02/01/2013       User2
3            Rejected       03/01/2013       User3
1            Approve        04/01/2013       User1
2            Approve        05/01/2013       User2
3            Approve        06/01/2013       User3
.                .              .              .
.                .              .              .
.                .              .              .

我想要这个

使用PIVOT是否可以?
LEVEL1 - User 1           LEVEL2 - User 2                  LEVEL3 - User 3
---------------------------------------------------------------------------
01/01/2013 - Approve      02/01/2013 - Approve             03/01/2013 - Rejected
04/01/2013 - Approve      05/01/2013 - Approve             06/01/2013 - Approve
         .                        .                                .
         .                        .                                .

注意:级数是动态的。例如完全批准一项可以是5级,6级等。因此,数据透视表中的列数是动态的。

最佳答案

是的,可以使用PIVOT函数完成此操作,我首先建议您查看查询的硬编码版本,以便在移至动态版本的查询之前可以查看查询的编写方式。

静态版本将类似于以下内容:

select [Level1 - User1], [Level2 - User2], [Level3 - User3]
from
(
  select 'Level'+cast(level as varchar(1)) + ' - '+ [user] col,
    convert(varchar(10), date, 101) +' - '+ action value,
    row_number() over(partition by level order by [user], date) rn
  from yt
) d
pivot
(
  max(value)
  for col in ([Level1 - User1], [Level2 - User2], [Level3 - User3])
) piv;

参见SQL Fiddle with Demo。您会注意到leveluser列被串联以创建新列,并且dateaction被串联以为每个列创建值。我还添加了row_number()为每行创建一个唯一值,当您在PIVOT中应用聚合函数时,这一点很重要。如果您不使用它,那么结果将只有一行。

由于您现在有了工作版本,因此可以轻松将其转换为动态版本:
DECLARE @cols AS NVARCHAR(MAX),
    @query  AS NVARCHAR(MAX)

select @cols = STUFF((SELECT distinct ',' + QUOTENAME('Level'+cast(level as varchar(1)) + ' - '+ [user])
                    from yt
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)')
        ,1,1,'')

set @query = 'SELECT ' + @cols + ' from
             (
                select ''Level''+cast(level as varchar(1)) + '' - ''+ [user] col,
                  convert(varchar(10), date, 101) +'' - ''+ action value,
                  row_number() over(partition by level order by [user], date) rn
                from yt
            ) x
            pivot
            (
                max(value)
                for col in (' + @cols + ')
            ) p '

execute(@query);

参见SQL Fiddle with Demo。两者的结果是:
|       LEVEL1 - USER1 |       LEVEL2 - USER2 |        LEVEL3 - USER3 |
-----------------------------------------------------------------------
| 01/01/2013 - Approve | 02/01/2013 - Approve | 03/01/2013 - Rejected |
| 04/01/2013 - Approve | 05/01/2013 - Approve |  06/01/2013 - Approve |

07-24 09:37
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