Question

我正在使用sql 2008 我的数据集看起来像

Entity    Type1    Type2    Balance 
1         A        R        100
1         B        Z        200
1         C        R        300
2         A        X        1000
2         B        Y        2000

我的输出应该是

Entity  A-Type2 A-Balance B-Type2 B-Balance C-Type2 C-Balance 
1       R       100       Z       200       R       300
2       X       1000      Y       2000              0

现在我开始编写一个数据透视查询，我想我可以使用MAX，因为每个Entity / Type1组合应该有一条记录。但无法弄清楚如何在一个支点中做两个字段。这可能吗？这是CTE可以提供帮助的东西吗？

Answer 1

最简单的是MAX的想法，但有一个CASE语句，例如：

SELECT
  Entity,
  MAX(CASE WHEN Type1 = 'A' THEN Type2 ELSE NULL END) AS AType2,
  MAX(CASE WHEN Type1 = 'A' THEN Balance ELSE NULL END) AS ABalance,
  MAX(CASE WHEN Type1 = 'B' THEN Type2 ELSE NULL END) AS BType2,
  MAX(CASE WHEN Type1 = 'B' THEN Balance ELSE NULL END) AS BBalance,
  MAX(CASE WHEN Type1 = 'C' THEN Type2 ELSE NULL END) AS CType2,
  MAX(CASE WHEN Type1 = 'C' THEN Balance ELSE NULL END) AS CBalance
FROM
  ...
GROUP BY
  Entity

换句话说，仅当Type1是特定值时使用该值（其他Type1值变为null）。

Answer 2

您只需使用条件聚合进行旋转：

select Entity,
       max(case when Type1 = 'A' then Type2 end) as A_Type2,
       max(case when Type1 = 'A' then Balance else 0 end) as A_Balance,
       max(case when Type1 = 'B' then Type2 end) as B_Type2,
       max(case when Type1 = 'B' then Balance else 0 end) as B_Balance,
       max(case when Type1 = 'C' then Type2 end) as C_Type2,
       max(case when Type1 = 'C' then Balance else 0 end) as C_Balance
from MyDataSet mds
group by Entity;

Answer 3

这是使用数据透视和查找来完成的。

SELECT 
data.Entity, 
ISNULL(a.Type2,'') AS [A-Type2], 
ISNULL([A-Balance],0) AS [A-Balance], 
ISNULL(b.Type2,'') AS [B-Type2], 
ISNULL([B-Balance],0) AS [B-Balance], 
ISNULL(c.Type2,'') AS [C-Type2], 
ISNULL([C-Balance],0) AS [C-Balance] 
FROM 
(
SELECT 
    Entity, 
    A AS [A-Balance], 
    B AS [B-Balance], 
    C AS [C-Balance] 
FROM
(
SELECT Entity, Type1, Balance FROM @table
) t
PIVOT (
    MAX(Balance)
    FOR Type1 IN ([A],[B],[C])
) piv
) data
LEFT OUTER JOIN @table a on a.Type1 = 'A' 
AND a.Entity = data.Entity AND a.Balance = [A-Balance] 
LEFT OUTER JOIN @table b on b.Type1 = 'B' 
AND b.Entity = data.Entity AND b.Balance = [B-Balance] 
LEFT OUTER JOIN @table c on c.Type1 = 'C' 
AND c.Entity = data.Entity AND c.Balance = [C-Balance]

使用Pivot或CTE来水平化查询

3 个答案: