获取父类别的层次类别

Question

我需要一个查询来选择具有给定父 ID 的所有子类别。我的表格如下所示：

|ID | Title | Description | ParentId
--------------------------------------
 1  | Games | ...         | NULL

等等..

是否可以通过 sql-query 解决这个问题？

给我游戏类别的所有子类别..

所有子类别可以有更多的子类别等等..

我的网站菜单需要这个来列出产品。
我的尝试 使用 CocoDb 去吧

;WITH parent 
  AS ( SELECT ParentId 
       FROM [CocoDb].[dbo].[Categories] 
       WHERE Id = 11 ) 
,tree AS ( SELECT x.ParentId, x.Id 
           FROM [CocoDb].[dbo].[Categories] x 
                 INNER JOIN [CocoDb].[dbo].[Categories] ON x.Id = 11
            UNION ALL 
           SELECT y.Id, y.ParentId FROM [CocoDb].[dbo].[Categories] y 
             INNER JOIN [CocoDb].[dbo].[Categories] t ON y.Id = t.ParentId )

解决方案：

;WITH parent 
  AS ( SELECT ParentId, Title, Id 
       FROM [CocoDb].[dbo].[Categories] 
       WHERE Id = 1
      ) 
,tree AS ( 
           SELECT x.ParentId, x.Id, x.Title 
           FROM [CocoDb].[dbo].[Categories] x 
                 INNER JOIN parent ON x.ParentId = parent.Id
           UNION ALL 
           SELECT y.ParentId, y.Id, y.Title 
           FROM [CocoDb].[dbo].[Categories] y 
            INNER JOIN tree t ON y.ParentId = t.Id 
          )
SELECT *
FROM Tree

Answer 1

;WITH parent AS 
    (
    SELECT Parent
    FROM Table1
    WHERE Child = @p0
    )    
,tree AS 
    (
    SELECT x.Parent, x.Child
    FROM Table1 x
    INNER JOIN parent ON x.Parent = parent.Parent
    UNION ALL
    SELECT y.Parent, y.Child
    FROM Table1 y
    INNER JOIN tree t ON y.Parent = t.Child
    )
      SELECT Parent, Child
      FROM tree

为您的查询更新

;WITH parent 
  AS ( SELECT ParentId 
       FROM [CocoDb].[dbo].[Categories] 
       WHERE Id = 11 
      ) 
,tree AS ( 
           SELECT x.ParentId, x.Id 
           FROM [CocoDb].[dbo].[Categories] x 
                 INNER JOIN parent ON x.ParentId = parent.ParentId
           UNION ALL 
           SELECT y.ParentId, y.Id 
           FROM [CocoDb].[dbo].[Categories] y 
            INNER JOIN tree t ON y.ParentId = t.Id 
          )
SELECT parent, Child 
FROM Tree

请确保在WITH 之前使用;，就像我在上述查询中使用的那样。

Answer 2

SELECT C.*
FROM <TABLE> C INNER JOIN <TABLE> P
ON P.ID=C.PARENTID
WHERE PARENTID=<GIVEN PARENTID>