15

我有一个格式如下的数据库：

 ID    TYPE   SUBTYPE    COUNT   MONTH
 1      A      Z          1       7/1/2008
 1      A      Z          3       7/1/2008
 2      B      C          2       7/2/2008
 1      A      Z          3       7/2/2008

我可以使用 SQL 将其转换为：

ID    A_Z   B_C   MONTH
1     4     0     7/1/2008
2     0     2     7/2/2008
1     0     3     7/2/2008

因此，TYPE,SUBTYPE被连接到新列中，并在和匹配COUNT的地方求和。IDMONTH

任何提示将不胜感激。这在 SQL 中是否可行，还是我应该手动编程？

数据库是 SQL Server 2005。

假设有 100 个TYPES等SUBTYPES，“A”和“Z”不应该是硬编码的，而是动态生成的。

4

2 回答 2

33

SQL Server 2005 提供了一个非常有用的 PIVOT 和 UNPIVOT 运算符，它允许您使用 PIVOT 和一些代码生成/动态 SQL 使此代码免维护

/*
CREATE TABLE [dbo].[stackoverflow_159456](
    [ID] [int] NOT NULL,
    [TYPE] [char](1) NOT NULL,
    [SUBTYPE] [char](1) NOT NULL,
    [COUNT] [int] NOT NULL,
    [MONTH] [datetime] NOT NULL
) ON [PRIMARY]
*/

DECLARE @sql AS varchar(max)
DECLARE @pivot_list AS varchar(max) -- Leave NULL for COALESCE technique
DECLARE @select_list AS varchar(max) -- Leave NULL for COALESCE technique

SELECT @pivot_list = COALESCE(@pivot_list + ', ', '') + '[' + PIVOT_CODE + ']'
        ,@select_list = COALESCE(@select_list + ', ', '') + 'ISNULL([' + PIVOT_CODE + '], 0) AS [' + PIVOT_CODE + ']'
FROM (
    SELECT DISTINCT [TYPE] + '_' + SUBTYPE AS PIVOT_CODE
    FROM stackoverflow_159456
) AS PIVOT_CODES

SET @sql = '
;WITH p AS (
    SELECT ID, [MONTH], [TYPE] + ''_'' + SUBTYPE AS PIVOT_CODE, SUM([COUNT]) AS [COUNT]
    FROM stackoverflow_159456
    GROUP BY ID, [MONTH], [TYPE] + ''_'' + SUBTYPE
)
SELECT ID, [MONTH], ' + @select_list + '
FROM p
PIVOT (
    SUM([COUNT])
    FOR PIVOT_CODE IN (
        ' + @pivot_list + '
    )
) AS pvt
'

EXEC (@sql)
于 2008-10-01T21:18:37.820 回答
6 
select id,
sum(case when type = 'A' and subtype = 'Z' then [count] else 0 end) as A_Z,
sum(case when type = 'B' and subtype = 'C' then [count] else 0 end) as B_C,
month
from tbl_why_would_u_do_this
group by id, month

您比我们的营销团队更能改变需求！如果您希望它是动态的，则需要依靠存储过程。

于 2008-10-01T20:12:55.217 回答