Question

我有两张表如下

表Person

表RelationHierarchy

ParentId   CHildId
   2         1
   3         2
   4         3

这将形成类似树的结构

ParentId和ChildId是Person Table

的Id列的外键

我需要编写可以获取顶级父级i-e Root的SQL。任何人都可以建议任何可以帮助我完成此任务的SQL

Answer 1

您可以使用recursive CTE来实现这一目标：

DECLARE @childID INT 
SET @childID  = 1 --chield to search

;WITH RCTE AS
(
    SELECT *, 1 AS Lvl FROM RelationHierarchy 
    WHERE ChildID = @childID

    UNION ALL

    SELECT rh.*, Lvl+1 AS Lvl FROM dbo.RelationHierarchy rh
    INNER JOIN RCTE rc ON rh.CHildId = rc.ParentId
)
SELECT TOP 1 id, Name
FROM RCTE r
inner JOIN dbo.Person p ON p.id = r.ParentId
ORDER BY lvl DESC

<强> SQLFiddle DEMO

编辑 - 针对所有孩子的最高级别父母的更新请求：

;WITH RCTE AS
(
    SELECT  ParentId, ChildId, 1 AS Lvl FROM RelationHierarchy 

    UNION ALL

    SELECT rh.ParentId, rc.ChildId, Lvl+1 AS Lvl 
    FROM dbo.RelationHierarchy rh
    INNER JOIN RCTE rc ON rh.ChildId = rc.ParentId
)
,CTE_RN AS 
(
    SELECT *, ROW_NUMBER() OVER (PARTITION BY r.ChildID ORDER BY r.Lvl DESC) RN
    FROM RCTE r

)
SELECT r.ChildId, pc.Name AS ChildName, r.ParentId, pp.Name AS ParentName
FROM CTE_RN r
INNER JOIN dbo.Person pp ON pp.id = r.ParentId
INNER JOIN dbo.Person pc ON pc.id = r.ChildId
WHERE RN =1

<强> SQLFiddle DEMO

EDIT2 - 让所有人在最后更改JOINS：

SELECT pc.Id AS ChildID, pc.Name AS ChildName, r.ParentId, pp.Name AS ParentName
FROM dbo.Person pc 
LEFT JOIN CTE_RN r ON pc.id = r.CHildId AND  RN =1
LEFT JOIN dbo.Person pp ON pp.id = r.ParentId

SQLFiddle DEMo

Answer 2

我使用此模式将层次结构中的项目与项目的根节点相关联。基本上递归层次结构，维护根节点的值作为附加到每一行的附加列。希望这会有所帮助。

    with allRows as (
        select ItemId, ItemName, ItemId [RootId],ItemName [RootName] 
        from parentChildTable
        where ParentItemId is null
        union all
        select a1.ItemId,a1.ItemName,a2.[RootId],a2.[RootName]
        from parentChildTable a1
        join allRows a2 on a2.ItemId = a1.ParentItemId
    )   

    select * from allRows

Answer 3

要查找所有顶级父级，请使用以下查询：

select p.Name
from Person p
where not exists
(select null
 from RelationHierarchy r
 where r.ChildId = p.Id)

SQLFiddle here。

要查找特定孩子的顶级父级，请使用：

with cte as
(select t.ParentId TopParent, t.ChildId 
 from RelationHierarchy t
 left join RelationHierarchy p on p.ChildId = t.ParentId
 where p.ChildId is null
 union all
 select t.TopParent TopParent, c.ChildId 
 from cte t
 join RelationHierarchy c on t.ChildId = c.ParentId)
select p.name
from cte h
join Person p on h.TopParent = p.Id
where h.ChildId=3 /*or whichever child is required*/

SQLFiddle here。

Answer 4

试试这个。

递归CTE将找到该人并走向层次结构，直到找不到父级。

-- This CTE will find the ancestors along with a measure of how far up
-- the hierarchy each ancestor is from the selected person.
with ancestor as (
  select ParentId as AncestorId, 0 as distance
  from RelationHierarchy
  where CHildId = ?

  union all

  select h.ParentId, a.distance + 1
  from ancestor a inner join RelationHierarchy rh on a.AncestorId = rh.ChildId
)
select AncestorId
from ancestor
where distance = (select max(distance) from ancestor)

Answer 5

这样的东西适用于上面的例子：

SELECT ParentId FROM RelationHierarchy 
WHERE ParentId NOT IN (SELECT CHildId FROM RelationHierarchy)

Answer 6

在“标准”SQL中执行此操作的唯一方法是假设树的最大深度，然后为每个级别执行连接。以下内容获得顶级ID：

select rh1.ChildId,
       coalesce(rh4.parentid, rh3.parentid, rh2.parentid, rh1.parentid) as topLevel
from RelationshipHierarchy rh1 left outer join
     RelationshipHierarchy rh2
     on rh1.parentId = rh2.childId left outer join
     RelationshipHierarchy rh3
     on rh2.parentId = rh3.childId left outer join
     RelationshipHierarchy rh4
     on rh3.parentId = rh4.childId;

如果您想要名称，可以加入：

select rh1.ChildId,
       coalesce(rh4.parentid, rh3.parentid, rh2.parentid, rh1.parentid) as topLevel,
       p.name
from RelationshipHierarchy rh1 left outer join
     RelationshipHierarchy rh2
     on rh1.parentId = rh2.childId left outer join
     RelationshipHierarchy rh3
     on rh2.parentId = rh3.childId left outer join
     RelationshipHierarchy rh4
     on rh3.parentId = rh4.childId left outer join
     Person p
     on p.id = coalesce(rh4.parentid, rh3.parentid, rh2.parentid, rh1.parentid);

Answer 7

使用路径获取所有顶级父母

路径格式：rootId /.../ parentId / nodeId /

select t1.path from nodes t1 inner join nodes t2
on t1.path like t2.path+'%' 
group by t1.path 
having len(t1.path)-len(replace(t1.path, '/', ''))
=min(len(t2.path)-len(replace(t2.path, '/', '')))

Answer 8

放手一搏：

    select id,name
    from person p
    where not exists
    (
    select 1 
    from relationhierarchy r
    where r.childid= p.id
    )
    and exists
    (
    select 1 
    from relationhierarchy r
    where r.parentid= p.id
    )

仅仅查看子ID是否存在是不够的，因为在您的示例中，E存在于person表中但不存在于relationshiphierarchy表中。

Answer 9

WITH CTE_MyTable AS (
    SELECT        Id, ParentId, NULL As RootParent, 1 As Lvl
    FROM            dbo.Ministry
    UNION ALL
    SELECT        a.id, b.ParentId, a.ParentId As RootParent, Lvl + 1
    FROM            CTE_MyTableAS a INNER JOIN
                                               dbo.MyTableAS b ON a.ParentId = b.Id
)
, CTE_Ministry_RN AS  (
    SELECT Id, RootParent, ROW_NUMBER() OVER (PARTITION BY Id ORDER BY Lvl DESC) RN
    FROM CTE_Ministry
)

SELECT Id, ISNULL(RootParent, Id) As RootParent
FROM CTE_Ministry_RN
WHERE RN = 1

在SQL中查找顶级父级

9 个答案: