Sql 将一组ID的行转换为列

考虑以下查询：

DECLARE @t1 TABLE(
    CompanyId INT, 
    DirectorName VARCHAR(100));

INSERT INTO @t1
   VALUES
      (1,'D11'),
      (1,'D12'),
      (1,'D13'),
      (1,'D14'),
      (1,'D15'),
      (1,'D16'),
      (2,'D21'),
      (2,'D22'),
      (2,'D23'),
      (2,'D24'),
      (2,'D25'),
      (2,'D26'),
      (2,'D27'),
      (2,'D28'),
      (2,'D29'),
      (2,'D210'),
      (3,'D31'),
      (3,'D32'),
      (3,'D33');

SELECT * FROM @t1 

它只返回该Id的companyId和一组控制器。如何生成以下输出：

 CompanyId | Director1| Director2| Director3|Director4| Director5| Director6| Director7| Director8| Director9| Director10|
-----------------------------------------------------------------------------------------------------------------------------
       1           D11        D12       D13       D14        D15         D16       NULL        NULL       NULL      NULL
       2           D21        D22       D23       D24        D25         D26       D27         D28        D29       D210 
       3           D31        D32       D33       NULL       NULL        NULL      NULL        NULL       NULL      NULL 

使上述查询变戏法的原因是，每家公司的董事人数不同。在上面的示例中，第2行具有最高数量的控制器，这意味着最终输出中其他ID的相关列将为空。如何创建上述输出

---

为了明确起见，在本例中，每个id（companyId）的结果不会超过10列（控制器）。

您可以使用以下解决方案：

通过使用，以及条件聚合，您可以做到这一点

只要每家公司的董事人数不超过10人

;with cteGetDirectorNum
AS(
    select
         T.CompanyId
        ,T.DirectorName
        ,DirectorNum    ='Director'+CONVERT(VARCHAR(10), Row_Number()over( partition by T.CompanyId order by T.CompanyId, T.DirectorName))
    from
        @t1     T
)
SELECT
     N.CompanyId
    ,Director1      = MAX(CASE WHEN N.DirectorNum = 'Director1' THEN n.DirectorName ELSE NULL END)
    ,Director2      = MAX(CASE WHEN N.DirectorNum = 'Director2' THEN n.DirectorName ELSE NULL END)
    ,Director3      = MAX(CASE WHEN N.DirectorNum = 'Director3' THEN n.DirectorName ELSE NULL END)
    ,Director4      = MAX(CASE WHEN N.DirectorNum = 'Director4' THEN n.DirectorName ELSE NULL END)
    ,Director5      = MAX(CASE WHEN N.DirectorNum = 'Director5' THEN n.DirectorName ELSE NULL END)
    ,Director6      = MAX(CASE WHEN N.DirectorNum = 'Director6' THEN n.DirectorName ELSE NULL END)
    ,Director7      = MAX(CASE WHEN N.DirectorNum = 'Director7' THEN n.DirectorName ELSE NULL END)
    ,Director8      = MAX(CASE WHEN N.DirectorNum = 'Director8' THEN n.DirectorName ELSE NULL END)
    ,Director9      = MAX(CASE WHEN N.DirectorNum = 'Director9' THEN n.DirectorName ELSE NULL END)
    ,Director10     = MAX(CASE WHEN N.DirectorNum = 'Director10' THEN n.DirectorName ELSE NULL END)
FROM
    cteGetDirectorNum N
GROUP BY N.CompanyId

---

SQL查询返回固定数量的列。如果你想要一个可变的列数，你需要使用动态SQL。在这个粒子问题中，我确信结果不会超过最大值10。所以我肯定知道最大值是多少。@Gordon-太多人试图分析选择前10名董事的逻辑是什么？每个Id的逻辑都是不同的（DirectorName），这意味着每个Id的逻辑都是不同的，我希望将不同的董事名作为列

;with cteGetDirectorNum
AS(
    select
         T.CompanyId
        ,T.DirectorName
        ,DirectorNum    ='Director'+CONVERT(VARCHAR(10), Row_Number()over( partition by T.CompanyId order by T.CompanyId, T.DirectorName))
    from
        @t1     T
)
SELECT
     N.CompanyId
    ,Director1      = MAX(CASE WHEN N.DirectorNum = 'Director1' THEN n.DirectorName ELSE NULL END)
    ,Director2      = MAX(CASE WHEN N.DirectorNum = 'Director2' THEN n.DirectorName ELSE NULL END)
    ,Director3      = MAX(CASE WHEN N.DirectorNum = 'Director3' THEN n.DirectorName ELSE NULL END)
    ,Director4      = MAX(CASE WHEN N.DirectorNum = 'Director4' THEN n.DirectorName ELSE NULL END)
    ,Director5      = MAX(CASE WHEN N.DirectorNum = 'Director5' THEN n.DirectorName ELSE NULL END)
    ,Director6      = MAX(CASE WHEN N.DirectorNum = 'Director6' THEN n.DirectorName ELSE NULL END)
    ,Director7      = MAX(CASE WHEN N.DirectorNum = 'Director7' THEN n.DirectorName ELSE NULL END)
    ,Director8      = MAX(CASE WHEN N.DirectorNum = 'Director8' THEN n.DirectorName ELSE NULL END)
    ,Director9      = MAX(CASE WHEN N.DirectorNum = 'Director9' THEN n.DirectorName ELSE NULL END)
    ,Director10     = MAX(CASE WHEN N.DirectorNum = 'Director10' THEN n.DirectorName ELSE NULL END)
FROM
    cteGetDirectorNum N
GROUP BY N.CompanyId