Question

我有两张桌子：

Product -< Category (1 product can have many categories)

Product表有三列：

ProductId, Name, Type
P1,Alpha Product,ClassA
P2,Beta Product,ClassB

Category表有四列：

CategoryId, Name, Value, ProductId
C1, Category1, 0.5, P1
C2, Category2, 0.75, P1
C3, Category1, 0.25, P2
C4, Category2, 0.15, P2

我想要实现的是每个产品一行，每个类别为一列，值为一行，例如：

ProductId, Category1, Category2
P1, 0.5, 0.75
P2, 0.25, 0.15

感谢任何帮助

Answer 1

修改以演示静态和动态方法

CREATE  TABLE #t
    (
      CategoryID CHAR(2)
    , NAME VARCHAR(15)
    , VALUE DECIMAL(3, 2)
    , ProductID CHAR(2)
    )
INSERT  INTO #t
        ( CategoryID
        , NAME
        , VALUE
        , ProductID 
        )
        SELECT  'C1'
              , 'Category1'
              , 0.5
              , 'P1'
        UNION
        SELECT  'C2'
              , 'Category2'
              , 0.75
              , 'P1'
        UNION
        SELECT  'C3'
              , 'Category1'
              , 0.25
              , 'P2'
        UNION
        SELECT  'C4'
              , 'Category2'
              , 0.15
              , 'P2'
SELECT  ProductID
      , Category1
      , Category2
FROM    ( SELECT    NAME
                  , VALUE
                  , ProductID
          FROM      #t t
        ) AS Src PIVOT ( AVG(VALUE) FOR NAME IN ( [Category1], [Category2] ) ) AS p


 --dynamically

--build your columns list 
DECLARE @columns VARCHAR(MAX)
SELECT  @columns = STUFF(( SELECT DISTINCT
                                    ',' + NAME
                           FROM     #t t
                           ORDER BY ',' + NAME
                         FOR
                           XML PATH('')
                         ), 1, 1, '')    

--build your sql statement 
DECLARE @sql VARCHAR(MAX)
SET @sql = REPLACE('SELECT  ProductID
      , |@columns|
FROM    ( SELECT    NAME
                  , VALUE
                  , ProductID
          FROM      #t t
        ) AS Src PIVOT ( AVG(VALUE) FOR NAME IN ( |@columns| ) ) AS p', '|@columns|', @columns)

 EXEC(@sql)

如何使用SQL Server 2008查询获得此结果？

1 个答案: