具有动态字段的SQL Server Pivot [英] SQL Server Pivot with Dynamic Fields

问题描述

试图找出在下表的日期字段上动态透视表的最佳方法.问题是这些日期会更改，因此我无法在数据透视表中对其进行硬编码.

Trying to figure out the best way to pivot a table dynamically on the date field in the following table. the issue is these dates change so I cant hard code them in the pivot statement.

id value date
1  55    2012-12-29 00:00:00:00
1  54    2012-10-29 00:00:00:00
1  89    2013-02-02 00:00:00:00
2  45    2012-12-29 00:00:00:00
2  54    2012-10-29 00:00:00:00
4  78    2012-12-29 00:00:00:00
4  90    2012-10-29 00:00:00:00
4  23    2012-10-29 00:00:00:00

我希望输出看起来像这样

I want the output to look like this

id 2012-12-29 00:00:00:00 2012-10-29 00:00:00:00 2013-02-02 00:00:00:00
1   55                    54                     89
2   45                    54                     null
4   78                    90                     23

推荐答案

由于使用的是SQL Server，因此可以使用PIVOT函数.

Since you are using SQL Server, then you can use the PIVOT function.

如果您的值已知，则可以对值进行硬编码:

If your values are known, then you can hard-code the values:

select *
from
(
  select id, value, date
  from yourtable
) src
pivot
(
  max(value)
  for date in ([2012-12-29], [2012-10-29], [2013-02-02])
) piv

请参见带演示的SQL提琴.

但是，如果它们未知，那么您将需要使用动态sql:

But if they are unknown, then you will need to use dynamic sql:

DECLARE @cols AS NVARCHAR(MAX),
    @query  AS NVARCHAR(MAX)

select @cols = STUFF((SELECT distinct ',' + QUOTENAME(convert(varchar(50), date, 120)) 
                    from yourtable
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

set @query = 'SELECT id, ' + @cols + ' from 
             (
                select id, value, convert(varchar(50), date, 120) date
                from yourtable
            ) x
            pivot 
            (
                max(value)
                for date in (' + @cols + ')
            ) p '

execute(@query)

请参见带演示的SQL提琴.

这两个查询的结果是:

| ID | 2012-10-29 00:00:00 | 2012-12-29 00:00:00 | 2013-02-02 00:00:00 |
------------------------------------------------------------------------
|  1 |                  54 |                  55 |                  89 |
|  2 |                  54 |                  45 |              (null) |
|  4 |                  90 |                  78 |              (null) |

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