選擇多行成列 - 動態旋轉

Question

這裏是最初的查詢返回：

plan_id Rep_id  rep_nm   employee_id Row_id 
6720  35   Robert Jones 160   1 
6720  36   Pam Smith  23    2 
6720  37   Erik Johnson 85    3 
6720  38   Sally Ells  212   4 
6719  40   Barbara Wax 168   5 

我需要讓行如下：

plan_id Rep_id1 rep_nm1  emp_id1 Rep_id2 rep_nm2 emp_id2 Rep_id3 etc. 
6720  35  Robert Jones 160  36  Pam Smith 23  Erik Johnson 
6719  40  Barbara Wax 168  NULL  NULL  NULL NULL  

最大rep_id*列會我嘗試搜索這樣一個示例的數據透視查詢，但沒有成功。

Answer 1

您沒有指定您正在使用的RDBMS，但是如果您使用的是SQL Server，則可以實現UNPIVOT和PIVOT函數。如果你知道你有多少價值去，那麼你可以硬編碼值：

select * 
from 
(
    select plan_id, value, col+cast(rn as varchar(10)) col 
    from 
    (
    select plan_id, 
     cast(rep_id as varchar(12)) rep_id, 
     rep_nm, 
     cast(employee_id as varchar(12)) employee_id, 
     row_number() over(partition by plan_id order by rep_id) rn 
    from yourtable 
) src 
    unpivot 
    (
    value 
    for col in (rep_id, rep_nm, employee_id) 
) up 
) un 
pivot 
(
    max(value) 
    for col in ([rep_id1], [rep_nm1], [employee_id1], 
       [rep_id2], [rep_nm2], [employee_id2], 
       [rep_id3], [rep_nm3], [employee_id3], 
       [rep_id4], [rep_nm4], [employee_id4]) 
) piv 

見SQL Fiddle with Demo

但如果你有一個未知的數值，那麼你可以使用類似這樣的動態SQL ：

DECLARE @colsUnpivot AS NVARCHAR(MAX), 
    @query AS NVARCHAR(MAX), 
    @colsPivot as NVARCHAR(MAX) 

select @colsUnpivot = stuff((select ','+quotename(C.name) 
     from sys.columns as C 
     where C.object_id = object_id('yourtable') and 
       C.name not in ('plan_id', 'Rep_id', 'Row_id') 
     for xml path('')), 1, 1, '') 

select @colsPivot = STUFF((SELECT ',' 
         + quotename(c.name 
         + cast(t.rn as varchar(10))) 
        from 
        (
         select row_number() over(partition by plan_id order by rep_id) rn 
         from yourtable 
        ) t 
        cross apply sys.columns as C 
        where C.object_id = object_id('yourtable') and 
         C.name not in ('plan_id', 'Rep_id', 'Row_id') 
        group by c.name, t.rn 
        order by t.rn 
      FOR XML PATH(''), TYPE 
      ).value('.', 'NVARCHAR(MAX)') 
     ,1,1,'') 


set @query 
    = 'select * 
     from 
     (
     select plan_id, value, col+cast(rn as varchar(10)) col 
     from 
     (
      select plan_id, 
      cast(rep_id as varchar(12)) rep_id, 
      rep_nm, 
      cast(employee_id as varchar(12)) employee_id, 
      row_number() over(partition by plan_id order by rep_id) rn 
      from yourtable 
     ) x 
     unpivot 
     (
      value 
      for col in ('+ @colsunpivot +') 
     ) u 
    ) src 
     pivot 
     (
     max(value) 
     for col in ('+ @colspivot +') 
    ) p' 

exec(@query) 

見SQL Fiddle with Demo

兩者都會產生相同的結果：

| PLAN_ID | EMPLOYEE_ID1 |  REP_NM1 | EMPLOYEE_ID2 | REP_NM2 | EMPLOYEE_ID3 |  REP_NM3 | EMPLOYEE_ID4 | REP_NM4 | 
------------------------------------------------------------------------------------------------------------------------------ 
| 6719 |   168 | Barbara Wax |  (null) | (null) |  (null) |  (null) |  (null) |  (null) | 
| 6720 |   160 | Robert Jones |   23 | Pam Smith |   85 | Erik Johnson |   212 | Sally Ells |