SQL 可变线的枢轴

Question

我必须将可变数量的行放入列中。我有类似的东西：

EMP                 EMP_ID  DIV_ID  ALLOCATION
Smith, Tom          3605    11300   20.00
Smith, Tom          13605   11310   80.00
Benetar, Pat        7460    11012   25.00
Benetar, Pat        7460    11015   75.00
Walkin, Chris       13892   11012   90.00
Walkin, Chris       13892   11015   10.00
Kent, Clark         12262   10015   50.00
Kent, Clark         12262   11210   25.00
Kent, Clark         12262   11220   25.00

我正在寻找的是这样的东西：

EMP           EMP_ID        DIV_ID_01     DIV_01_ALOC    DIV_ID_02     DIV_02_ALOC    DIV_ID_03     DIV_03_ALOC
Smith, Tom    3605          11300         20.00          11310         80.00
Benetar, Pat  13605         11012         25.00          11015         75.00
Walkin, Chris 13892         11012         90.00          11015         10.00
Kent, Clark   12262         11015         50.00          11210         25.00          11220         25.00

我想避免使用大量的 CASE 语句。我现在正在尝试使用枢轴，但在使用 headers.

时遇到了困难

Answer 1

更新：

经过几次尝试，我想出了下面的解决方案，它利用两个 PIVOT 函数和一个 GROUP BY 来匹配您的预期结果。

这是下面的代码。注意：这适用于 SQL Server 2005+

with testdata(Emp, EMP_ID, DIV_ID, ALLOCATION)
as
(
select 'Smith, Tom',3605, 11300,20.00
union all
select 'Smith, Tom',3605, 11310, 80.00
union all
select 'Benetar, Pat',7460, 11012,25.00
union all
select 'Benetar, Pat',7460, 11015,75.00
union all
select 'Walkin, Chris',13892, 11012, 90.00
union all
select 'Walkin, Chris', 13892, 11015, 10.00
union all
select 'Kent, Clark', 12262, 10015, 50.00
union all
select 'Kent, Clark', 12262, 11210, 25.00
union all
select 'Kent, Clark', 12262, 11220, 25.00
)       
SELECT Emp
,EMP_ID
,MAX([Div1]) AS DIV_ID_01
,MAX([Alloc1]) AS DIV_01_ALOC
,MAX([Div2]) AS DIV_ID_02
,MAX([Alloc2]) AS DIV_02_ALOC
,MAX([Div3]) AS DIV_ID_03
,MAX([Alloc3]) AS DIV_03_ALOC
FROM (
    SELECT *
    ,cast(dense_rank() OVER (PARTITION BY emp_id 
            ORDER BY div_id asc) AS nvarchar) AS [emp_rnk]
    ,'Alloc' + cast(dense_rank() OVER (PARTITION BY emp_id 
            ORDER BY div_id asc) AS nvarchar) AS [piv_Alloc_rnk] 
    ,'Div' + cast(dense_rank() OVER (PARTITION BY emp_id 
            ORDER BY div_id asc) AS nvarchar) AS [piv_Div_rnk]
FROM testdata td
) query

/* After both PIVOT functions are compplete, it still returns a single row for each EMP_ID. 
 So further aggregation is needed to 'flatten' the result. */

PIVOT (Max(Div_id) FOR [piv_Div_rnk] IN ([Div1],[Div2],[Div3])) AS pivot1
PIVOT (Max(Allocation) FOR [piv_Alloc_rnk] in([Alloc1],[Alloc2],[Alloc3])) AS pivot2

/* Since there is only one value in each of the columns created by the PIVOTS for each EMP_ID taking 
the MAX() value and grouping by EMP and EMP_ID flattens the result down to the desired output. */ 

GROUP BY emp, emp_id
ORDER BY DIV_ID_01 DESC

Answer 2

仅供参考，如果您尝试在此处使用动态 PIVOT，您最终将需要一个类似如下的查询。

SELECT  [EMP],
        [EMP_ID],
        MIN(DIV_ID_1) [DIV_ID_1],
        SUM(DIV_1_ALOC) [DIV_1_ALOC],
        MIN(DIV_ID_2) [DIV_ID_2],
        SUM(DIV_2_ALOC) [DIV_2_ALOC],
        MIN(DIV_ID_3) [DIV_ID_3],
        SUM(DIV_3_ALOC) [DIV_3_ALOC]
FROM    (SELECT [EMP],
                [EMP_ID],
                [DIV_ID],
                [ALLOCATION],
                CONCAT('DIV_ID_',DENSE_RANK () OVER (PARTITION BY [EMP] ORDER BY [DIV_ID])) ID_RN,
                CONCAT('DIV_',DENSE_RANK () OVER (PARTITION BY [EMP] ORDER BY [DIV_ID]),'_ALOC') ALLOC_RN
         FROM   EmpTable
        ) t 
PIVOT   ( 
        MIN([DIV_ID]) 
        FOR ID_RN IN ([DIV_ID_1],[DIV_ID_2],[DIV_ID_3]) ) p1 
PIVOT   ( 
        SUM([ALLOCATION]) 
        FOR ALLOC_RN IN ([DIV_1_ALOC],[DIV_2_ALOC],[DIV_3_ALOC]) ) p2
GROUP BY [EMP],
        [EMP_ID]

由于双主元，您需要动态创建 SELECT 和 PIVOT 列。

另一方面，如果您使用 CASE 语句，您只需要动态创建 SELECT，因为该查询看起来像

SELECT  [EMP],
        [EMP_ID],
        MIN(CASE WHEN RN = 1 THEN [DIV_ID] END) [DIV_ID_1],
        SUM(CASE WHEN RN = 1 THEN [ALLOCATION] END) [DIV_1_ALOC],
        MIN(CASE WHEN RN = 2 THEN [DIV_ID] END) [DIV_ID_2],
        SUM(CASE WHEN RN = 2 THEN [ALLOCATION] END) [DIV_2_ALOC],
        MIN(CASE WHEN RN = 3 THEN [DIV_ID] END) [DIV_ID_3],
        SUM(CASE WHEN RN = 3 THEN [ALLOCATION] END) [DIV_3_ALOC]
FROM    (
            SELECT  *,
                    DENSE_RANK () OVER (PARTITION BY [EMP] ORDER BY [DIV_ID]) RN 
            FROM    EmpTable
        ) t
GROUP BY [EMP],
        [EMP_ID]

您的动态声明应该类似于

DECLARE @CaseSelect VARCHAR(MAX)
SELECT  @CaseSelect = COALESCE(@CaseSelect + ',','') 
                + 'MIN(CASE WHEN RN = ' + RN + ' THEN [DIV_ID] END) [DIV_ID_' + RN + '],'
                + 'SUM(CASE WHEN RN = ' + RN + ' THEN [ALLOCATION] END) [DIV_' + RN + '_ALOC]'
FROM    (
    SELECT DISTINCT CONVERT(VARCHAR(2),DENSE_RANK () OVER (PARTITION BY [EMP] ORDER BY [DIV_ID])) RN 
    FROM EmpTable 
) t 
ORDER BY RN

DECLARE @SQL VARCHAR(MAX)
SET     @SQL = '
    SELECT  [EMP],
            [EMP_ID], '
            + @CaseSelect + '
    FROM    (
        SELECT  *,
                DENSE_RANK () OVER (PARTITION BY [EMP] ORDER BY [DIV_ID]) RN 
        FROM    EmpTable
    ) t
    GROUP BY [EMP], [EMP_ID]
'

EXEC(@SQL)

将 EmpTable 替换为您实际的 table 课程名称。

SQL 可变线的枢轴

SQL pivot with variable lines

sql

pivot

dynamic