Question

我目前正在运行查询

SELECT [PriceAttributeID]
  ,[PriceID]
  ,[AttributeID]
  ,[PriceAttributeComparator]
  ,[PriceAttributeMin]
  ,[PriceAttributeMax]
FROM [PriceAttribute]

给出输出

1   2   1   1   S   NULL
2   3   1   1   M   NULL
3   4   1   1   L   NULL
4   5   1   1   L   NULL
5   5   2   1   Black   NULL

我想获得输出（_Comp，_Min和_Max与PriceAttributeComparator，PriceAttributeMin和PriceAttributeMax）< / p>

PriceID    1_Comp    1_Min    1_Max    2_Comp    2_Min    2_Max
      2         1        S     NULL      NULL     NULL     NULL
      3         1        M     NULL      NULL     NULL     NULL
      4         1        L     NULL      NULL     NULL     NULL
      5         1        L     NULL         1    Black     NULL

同样的查询也应该有1_和2_前缀为4_，5_，19_和32_或任何其他不确定数量的ID基于当时表中的内容。

我尝试了一个PIVOT表，但我是他们的新手并没有关于如何创建我想要做的事情的第一个线索。

Answer 1

您可能使用PIVOT函数的部分问题是由于您要将多个列应用于该函数。如果你想使用PIVOT函数，那么我建议首先取消PriceAttributeComparator，PriceAttributeMin和PriceAttributeMax列的取消。当您取消忽略数据时，您将不再拥有多个列，您将拥有多行，然后您可以将数据透视应用于所有适当的值。

您没有指定正在使用的SQL Server版本，但您可以使用CROSS APPLY和UNION ALL来取消列的删除：

select priceid, 
  col = cast(attributeid as varchar(10))+'_'+ col, 
  value
from 
(
  select PriceID, 
    AttributeID, 
    comp = cast(PriceAttributeComparator as varchar(10)),
    [min] = cast(PriceAttributeMin as varchar(10)), 
    [max] = cast(PriceAttributeMax as varchar(10))
  from PriceAttribute
) d
cross apply
(
  select 'comp', comp union all
  select 'min', [min] union all
  select 'max', [max] 
) c (col, value)

见Demo。此过程会将您的数据转换为以下格式：

| PRICEID |    COL |  VALUE |
-----------------------------
|       2 | 1_comp |      1 |
|       2 |  1_min |      S |
|       2 |  1_max | (null) |
|       3 | 1_comp |      1 |
|       3 |  1_min |      M |
|       3 |  1_max | (null) |

一旦数据在多行中，您就可以将PIVOT函数应用于col中的值：

select priceid,
  [1_comp], [1_min], [1_max], [2_comp], [2_min], [2_max]
from
(
  select priceid, 
    col = cast(attributeid as varchar(10))+'_'+ col, 
    value
  from 
  (
    select PriceID, 
      AttributeID, 
      comp = cast(PriceAttributeComparator as varchar(10)),
      [min] = cast(PriceAttributeMin as varchar(10)), 
      [max] = cast(PriceAttributeMax as varchar(10))
    from PriceAttribute
  ) d
  cross apply
  (
    select 'comp', comp union all
    select 'min', [min] union all
    select 'max', [max] 
  ) c (col, value)
) src
pivot
(
  max(value)
  for col in ([1_comp], [1_min], [1_max], [2_comp], [2_min], [2_max])
) piv;

见SQL Fiddle with Demo。

如果您拥有已知数量的值，但上述版本的效果很好，但如果值未知，则需要使用动态SQL来获得结果：

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

select @cols = STUFF((SELECT ',' + QUOTENAME(cast(attributeid as varchar(10))+'_'+ col) 
                    from
                    (
                      select distinct attributeid
                      from priceattribute
                    ) d
                    cross apply
                    (
                      select 'comp', 1 union all
                      select 'min', 2 union all
                      select 'max', 3 
                    ) c (col, so)
                    group by attributeid, col, so
                    order by attributeid, so
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

set @query = 'SELECT priceid, ' + @cols + ' 
            from 
            (
                select priceid, 
                  col = cast(attributeid as varchar(10))+''_''+ col, 
                  value
                from 
                (
                  select PriceID, 
                    AttributeID, 
                    comp = cast(PriceAttributeComparator as varchar(10)),
                    [min] = cast(PriceAttributeMin as varchar(10)), 
                    [max] = cast(PriceAttributeMax as varchar(10))
                  from PriceAttribute
                ) d
                cross apply
                (
                  select ''comp'', comp union all
                  select ''min'', [min] union all
                  select ''max'', [max] 
                ) c (col, value)
            ) x
            pivot 
            (
                max(value)
                for col in (' + @cols + ')
            ) p '

execute sp_executesql @query;

见SQL Fiddle with Demo。这些解决方案将产生结果：

| PRICEID | 1_COMP | 1_MIN |  1_MAX | 2_COMP |  2_MIN |  2_MAX |
----------------------------------------------------------------
|       2 |      1 |     S | (null) | (null) | (null) | (null) |
|       3 |      1 |     M | (null) | (null) | (null) | (null) |
|       4 |      1 |     L | (null) | (null) | (null) | (null) |
|       5 |      1 |     L | (null) |      1 |  Black | (null) |

Answer 2

使用条件聚合而不是数据透镜可能最简单：

SELECT PriceID,
       max(case when AttributeID = 1 then PriceAttributeComparator end) as comp_1,
       max(case when AttributeID = 1 then PriceAttributeMin end) as min_1,
       max(case when AttributeID = 1 then PriceAttributeMax end) as max_1,
       max(case when AttributeID = 2 then PriceAttributeComparator end) as comp_2,
       max(case when AttributeID = 2 then PriceAttributeMin end) as min_2,
       max(case when AttributeID = 2 then PriceAttributeMax end) as max_2
FROM PriceAttribute pa
group by PriceId;

透视表将行转换为列

2 个答案: