SQL Server 2005-CTE，保留值并插入数据集中

Question

可以说您有一个这样的表（SQL SERVER 2005）

pairID childID parentID
 0       1      2
 1       2      3
 2       3      4

您拥有返回此数据集的CTE：

pairID childID parentID level
 0       1      2        2
 1       2      3        1
 2       3      4        0

您如何保存初始子ID，以便获取此结果集：

pairID childID parentID level
 0       1      2        2
 1       1      3        1
 2       1      4        0

所以基本上我在做的是保留原始的孩子id并返回它而不是其他...

到目前为止，这是CTE查询，效果很好：

WITH TESTER AS (SELECT a.PairID,
                a.ChildID,
                a.ParentID,
                0 AS Level
                FROM
                BusinessHierarchy AS a 
                LEFT OUTER JOIN BusinessHierarchy AS a2 
                ON a.ParentID = a2.ChildID
                WHERE (a2.PairID IS NULL)
                UNION ALL
                SELECT b.PairID, b.ChildID, b.ParentID, oh.Level + 1 AS Level
                FROM BusinessHierarchy AS b INNER JOIN
                TESTER AS oh ON b.ParentID = oh.ChildID)
SELECT PairID, ChildID, ParentID, Level
 FROM  TESTER AS x
 ORDER BY Level, ChildID, ParentID

Answer 1

如果先（放入变量中），然后再使用变量，则可以得到该值。

DECLARE @StartingId int

SELECT
    @StartingId = a.PairID
FROM BusinessHierarchy AS a 
LEFT OUTER JOIN BusinessHierarchy AS a2 ON a.ParentID = a2.ChildID
WHERE (a2.PairID IS NULL)


WITH TESTER AS (SELECT a.PairID,
            a.ChildID,
            a.ParentID,
            0 AS Level
            FROM
            BusinessHierarchy AS a 
            WHERE (a.PairID = @StartingId)
            UNION ALL
            SELECT b.PairID, b.ChildID, b.ParentID, oh.Level + 1 AS Level
            FROM BusinessHierarchy AS b INNER JOIN
            TESTER AS oh ON b.ParentID = oh.ChildID)

SELECT PairID, @StartingId, ParentID, Level
FROM  TESTER AS x
ORDER BY Level, ChildID, ParentID

Answer 2

未经测试，但是您尝试过吗？

;WITH My_CTE AS
(
     SELECT
          BH1.PairID,
          BH1.ChildID AS BaseID,
          BH1.ChildID,
          BH1.ParentID,
          0 AS Level
     FROM
          BussinessHierarchy BH1
     LEFT OUTER JOIN BussinessHierarchy BH2 ON
          BH1.ParentID = BH2.ChildID
     WHERE
          BH2.PairID IS NULL
     UNION ALL
     SELECT
          BH3.PairID,
          CTE.BaseID,
          BH3.ChildID,
          BH3.ParentID,
          CTE.Level + 1 AS Level
     FROM
          My_CTE CTE
     INNER JOIN BussinessHierarchy BH3 ON
          BH3.ParentID = CTE.ChildID
     )
SELECT
     PairID,
     BaseID,
     ParentID,
     Level
FROM
     My_CTE
ORDER BY
     Level,
     BaseID,
     ParentID

Answer 3

恐怕您的CTE令我感到困惑，因此，我将其重写如下，它可以提供您所要求的结果。 这符合您的要求吗？

WITH List (pairID, childId, parentId, level, originalid )
AS
(
    -- Anchor member definition
    select pairID, childID, parentID, 0 as level, ChildID as originalid
    FROM    
    BusinessHeirarchy bh
    where bh.PairID = 0


    UNION ALL

    -- Recursive member definition
    select j.pairId, j.childID, j.parentID, lst.level +1 as level, lst.originalid
    from BusinessHeirarchy j inner join List lst 
    on  (lst.parentId = j.ChildID)

)

select * from list;

显然，您可以根据需要使用输出列和顺序，但是该数据与所需内容匹配。

使用sql时要注意的一件事是，我基于对的对数限制0限制了锚查询，因为您的示例数据没有空值。 如果您需要空检查来拉出锚，这应该很容易更改。

然后，我简单地加入父子关系，并使用附加列OriginalId来保存锚点查询中的第一个childId。