SQL Server-以多对多的关系获取行中的所有子级? [英] SQL Server - Get all children of a row in many-to-many relationship?

问题描述

我正在尝试在SQL Server中编写一个递归查询，该查询基本上列出了给定父级的父子级层次结构.父母可以有多个孩子，而一个孩子可以属于多个父母，因此它以多对多关系存储.

I'm trying to write a recursive query in SQL Server that basically lists a parent-child hierarchy from a given parent. A parent can have multiple children and a child can belong to multiple parents so it is stored in a many-to-many relation.

我从另一个有点相关的问题中修改了以下查询，但这并没有完全解决问题，仅选择了第一级子级...

I modified the following query from another somewhat related question, however this doesn't go all the way up to the tree and only selects the first level child...

DECLARE @ObjectId uniqueidentifier
SET @ObjectId = '1A213431-F83D-49E3-B5E2-42AA6EB419F1';

WITH Tree AS
(
   SELECT A.*
   FROM Objects_In_Objects A
   WHERE A.ParentObjectId = @ObjectId

   UNION ALL

   SELECT B.*
   FROM Tree A
   JOIN Objects_In_Objects B
   ON A.ParentObjectId = B.ObjectId
)
SELECT *
FROM Tree
INNER JOIN Objects ar on tree.ObjectId = ar.ObjectId

有人知道如何修改查询，使其一直沿树"走下去吗?还是使用上述结构无法做到这一点?

Does anyone know how to modify the query to go all the way down the 'tree'? Or is this not possible using the above construction?

对象

列:ObjectId | Name

Objects_In_Objects

列:ObjectId | ParentObjectId

样本数据:

对象

ObjectId                             | Name
1A213431-F83D-49E3-B5E2-42AA6EB419F1 | Main container  
63BD908B-54B7-4D62-BE13-B888277B7365 | Sub container  
71526E15-F713-4F03-B707-3F5529D6B25E | Sub container 2  
ADA9A487-7256-46AD-8574-0CE9475315E4 | Object in multiple containers

对象中的对象

ObjectId                             | ParentObjectId                    
ADA9A487-7256-46AD-8574-0CE9475315E4 | 71526E15-F713-4F03-B707-3F5529D6B25E
ADA9A487-7256-46AD-8574-0CE9475315E4 | 63BD908B-54B7-4D62-BE13-B888277B7365
63BD908B-54B7-4D62-BE13-B888277B7365 | 1A213431-F83D-49E3-B5E2-42AA6EB419F1
71526E15-F713-4F03-B707-3F5529D6B25E | 1A213431-F83D-49E3-B5E2-42AA6EB419F1

推荐答案

这样的递归CTE(公用表表达式)将一直沿用 .

Such a recursive CTE (Common Table Expression) will goo all the way .

尝试一下:

;WITH Tree AS
(
   SELECT A.ObjectID, A.ObjectName, o.ParentObjectID, 1 AS 'Level'
   FROM dbo.Objects A
   INNER JOIN dbo.Objects_In_Objects o ON A.ObjectID = o.ParentObjectID
   WHERE A.ObjectId = @ObjectId           -- use the A.ObjectId here

   UNION ALL

   SELECT A2.ObjectID, A2.ObjectName, B.ParentObjectID, t.Level + 1 AS 'Level'
   FROM Tree t 
   INNER JOIN dbo.Objects_In_Objects B ON B.ParentObjectID = t.ObjectID
   INNER JOIN dbo.Objects A2 ON A2.ObjectId = B.ObjectId        
)
SELECT *
FROM Tree
INNER JOIN dbo.Objects ar on tree.ObjectId = ar.ObjectId

如果您更改此设置-这项功能现在对您有用吗? (我添加了Level列-通常有助于理解层次结构中每一行的深度")

If you change this - does this work for you now? (I added a Level column - typically helps to understand the "depth" in the hierarchy for every row)

我似乎确实在我的SQL Server实例上获得了正确的输出，至少...

I do seem to get the proper output on my SQL Server instance, at least...

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