Question

我有一个持有分层结构的表，所以基本上它有3列：

enter image description here

我想要的是从这个表中选择一系列ID，例如：

Id IN (1,4,8,18)

导致：

enter image description here

换句话说，一行必须与所有父母和孩子一起进入结果集。

我怎么能解决这个问题呢？提前致谢

Answer 1

您可以使用CTE执行此操作：

DECLARE @t TABLE ( ID INT, ParentID INT )

INSERT  INTO @t
VALUES  ( 1, NULL ),
        ( 2, 1 ),
        ( 3, 2 ),
        ( 4, 3 ),
        ( 6, NULL ),
        ( 7, 6 ),
        ( 8, 7 ),
        ( 9, 8 ),
        ( 10, 9 ),
        ( 11, 10 ),
        ( 13, NULL ),
        ( 14, 13 ),
        ( 15, 14 ),
        ( 17, NULL ),
        ( 18, 17 ),
        ( 19, 18 ),
        ( 20, 19 );

WITH    ctep
          AS ( SELECT   *
               FROM     @t
               WHERE    ID IN ( 1, 4, 8, 18 )
               UNION ALL
               SELECT   t.*
               FROM     @t t
                        JOIN ctep ON t.ParentID = ctep.ID
             ),
        ctec
          AS ( SELECT   *
               FROM     @t
               WHERE    ID IN ( 1, 4, 8, 18 )
               UNION ALL
               SELECT   t.*
               FROM     @t t
                        JOIN ctec ON t.ID = ctec.ParentID
             )
    SELECT  * FROM    ctep
    UNION
    SELECT  * FROM    ctec

以下是2个CTE，用于获取父母和孩子。最后，你将这两个结果结合起来以获得不同的行。

我有一个小虫子。编辑...

Answer 2

将您的任务分成两个步骤

找到最顶级的父母

查找所有死者

WITH ToTopParent AS
(
    SELECT Id, ParentId
    FROM yourTable
    WHERE Id IN (1,4,8,18) 

    UNION ALL

    SELECT T.Id, T.ParentId
    FROM ToTopParent TTP
    JOIN yourTable T ON TTP.ParentId = T.Id
),
AllDecedents AS
(
    SELECT Id, Name, ParentID
    FROM yourTable 
    WHERE id IN (SELECT Id FROM ToTopParent WHERE ParentId IS NULL)

    UNION ALL

    SELECT T.Id, T.Name, T.ParentID
    FROM yourTable T
    JOIN AllDecedents ON T.ParentId = AllDecedents.Id
)
SELECT * FROM AllDecedents

Answer 3

您可以使用递归公用表表达式（CTE）。这种任务非常好。下面我假设tbl是你的表名。

WITH UserCTE AS
(

SELECT Id, name, ParentId
FROM tbl
WHERE Id in (1,4,8,18)

UNION ALL

SELECT P.Id, P.name, P.ParentId
FROM UserCTE AS C --- C for child
JOIN tbl AS P --- P for parent
ON C.ParentId = P.Id

)
SELECT Id, name, ParentId
FROM UserCTE;

您也可以尝试使用

SELECT DISTINCT Id, name, ParentId
FROM UserCTE;

如果您发现某些记录多次返回。

根据ID的范围从层次结构中进行选择

3 个答案: