sql - 是否可以使用 SQL Server 使用相同的数据透视列进行多个数据透视

Question

我正面临以下挑战。我需要在同一列上旋转表数据两次。这是数据的屏幕截图。

我希望每个项目 ID 都有一行，其中包含每年的购买价值和销售价值。我尝试通过选择“年份”列两次，对其进行格式化，以便每个销售年份以“S”为前缀，每个购买年份以“P”开头，并使用 2 个枢轴围绕 2 年列旋转. 这是 SQL 查询（用于 SQL Server 2008）：

SELECT [Item ID], 
        [P2000],[P2001],[P2002],[P2003],
        [S2000],[S2001],[S2002],[S2003]
FROM 
(

SELECT [Item ID]
      ,'P' + [Year] AS YearOfPurchase
      ,'S' + [Year] AS YearOfSelling

  ,[Purchasing value]
  ,[Selling value]
  FROM [ItemPrices]
) AS ALIAS

PIVOT 
(
MIN ([Purchasing value]) FOR [YearOfPurchase] in ([P2000],[P2001],[P2002],[P2003])
)
AS pvt

PIVOT 
(
MIN ([Selling value]) FOR [YearOfSelling] in ([S2000],[S2001],[S2002],[S2003])
)
AS pvt2

结果并不完全是我所希望的（见下图）：

如您所见，每个项目 ID 仍然不止一行。有没有办法将行数减少到每个项目正好一个？所以它看起来有点像下面的 Excel 屏幕截图？

Answer 1

我的建议是同时应用UNPIVOT和PIVOT函数来获得结果。

这UNPIVOT会将PurchasingValue和SellingValue列转换为行。完成此操作后，您可以将数据转换为结果。

代码将是：

select *
from
(
  select itemid, 
    case 
      when col = 'PurchasingValue' then 'P'
      when col = 'SellingValue' then 'S'
    end + cast(year as varchar(4)) new_col,
    value
  from yourtable
  unpivot
  (
    value
    for col in ([PurchasingValue], [SellingValue])
  ) unpiv
) src
pivot
(
  max(value)
  for new_col in (P2000, P2001, P2002, P2003,
                  S2000, S2001, S2002, S2003)
) piv;

请参阅SQL Fiddle with Demo。结果是：

| ITEMID | P2000 | P2001 | P2002 | P2003 | S2000 | S2001 | S2002 | S2003 |
--------------------------------------------------------------------------
|      1 |  1000 |  1100 |  1200 |  1300 |   900 |   990 |  1080 |  1170 |
|      2 |   500 |   550 |   600 |   650 |   450 |   495 |   540 |   585 |

在 SQL Server 2008+ 中，您可以将CROSS APPLYwithVALUES与PIVOT函数一起使用：

select *
from
(
  select itemid,
    col+cast(year as varchar(4)) new_col,
    value
  from yourtable
  cross apply
  (
    VALUES
        (PurchasingValue, 'P'),
        (SellingValue, 'S')
   ) x (value, col)
) src
pivot
(
  max(value)
  for new_col in (P2000, P2001, P2002, P2003,
                  S2000, S2001, S2002, S2003)
) piv

请参阅带有演示的 SQL Fiddle

Answer 2

旋转多列的一种简单方法是仅使用 Aggregate(Case) 表达式。

SELECT  [Item ID],
        [P2000] = SUM(CASE WHEN [Year] = 2000 THEN [Purchasing value] END),
        [P2001] = SUM(CASE WHEN [Year] = 2001 THEN [Purchasing value] END),
        [P2002] = SUM(CASE WHEN [Year] = 2002 THEN [Purchasing value] END),
        [P2003] = SUM(CASE WHEN [Year] = 2003 THEN [Purchasing value] END),
        [S2000] = SUM(CASE WHEN [Year] = 2000 THEN [Selling value] END),
        [S2001] = SUM(CASE WHEN [Year] = 2001 THEN [Selling value] END),
        [S2002] = SUM(CASE WHEN [Year] = 2002 THEN [Selling value] END),
        [S2003] = SUM(CASE WHEN [Year] = 2003 THEN [Selling value] END)
FROM    ItemPrices
GROUP BY [Item ID]

Answer 3

使用 GROUP BY ItemID，并在每个结果列上使用聚合函数 SUM(isnull(value,0))。