给定具有hierarchyid
类型列的表,如何编写查询以返回作为特定节点的祖先的所有行?
有一个IsDescendantOf()
函数,非常适合获取孩子,但没有相应的IsAncestorOf()
函数来返回祖先(并且缺少GetAncestors()
函数似乎是一个疏忽。)
给定具有hierarchyid
类型列的表,如何编写查询以返回作为特定节点的祖先的所有行?
有一个IsDescendantOf()
函数,非常适合获取孩子,但没有相应的IsAncestorOf()
函数来返回祖先(并且缺少GetAncestors()
函数似乎是一个疏忽。)
最常用的方法是递归公用表表达式 (CTE)
WITH Ancestors(Id, [Name], AncestorId) AS
(
SELECT
Id, [Name], Id.GetAncestor(1)
FROM
dbo.HierarchyTable
WHERE
Name = 'Joe Blow' -- or whatever you need to select that node
UNION ALL
SELECT
ht.Id, ht.[Name], ht.Id.GetAncestor(1)
FROM
dbo.HierarchyTable ht
INNER JOIN
Ancestors a ON ht.Id = a.AncestorId
)
SELECT *, Id.ToString() FROM Ancestors
(改编自Simon Ince 博客文章)
Simon Ince 还提出了第二种方法,他基本上只是颠倒了条件——而不是检测那些是目标人的祖先的人条目,他把检查转过来:
DECLARE @person hierarchyid
SELECT @person = Id
FROM dbo.HierachyTable
WHERE [Name] = 'Joe Blow';
SELECT
Id, Id.ToString() AS [Path],
Id.GetLevel() AS [Level],
Id.GetAncestor(1),
Name
FROM
dbo.HierarchyTable
WHERE
@person.IsDescendantOf(Id) = 1
这将从您的表中选择所有行,其中您感兴趣的目标人是层次结构下的任何级别的后代。所以这将找到目标人的直接和非直接祖先一直到根。
这是一个包含在单个选择中的答案:
SELECT t1.Id.ToString() as Path, t1.Name
FROM (SELECT * FROM HierarchyTable
WHERE Name = 'Joe Blow') t2,
HierarchyTable t1
WHERE t2.Id.IsDescendantOf(t1.Id) = 1
Declare @hid hierarchyid=0x5D10 -- Child hierarchy id
SELECT
*
FROM
dbo.TableName
WHERE
@hid.IsDescendantOf(ParentHierarchyId) = 1
我编写了一个用户定义的表值函数,它将一个 hierarchyid 值扩展为它的组成祖先。然后可以将输出连接回 hierarchyid 列,以专门获取这些祖先。
alter function dbo.GetAllAncestors(@h hierarchyid, @ReturnSelf bit)
returns table
as return
select @h.GetAncestor(n.Number) as h
from dbo.Numbers as n
where n.Number <= @h.GetLevel()
or (@ReturnSelf = 1 and n.Number = 0)
union all
select @h
where @ReturnSelf = 1
go
要使用它:
select child.ID, parent.ID
from dbo.yourTable as child
cross apply dbo.GetAllAncestors(child.hid, 1) as a
join dbo.yourTable as parent
on parent.hid = a.h
完善 Ben Thui 的答案,我认为这是迄今为止最好的答案......
下面的方法允许在一个查询中不仅检索一个,而且可能检索几个叶行及其祖先。
Create Or Alter Function dbo.GetAllAncestors
(
@Path HierarchyId,
@WithSelf Bit = 1,
@MinLevel Int = 0,
@MaxLevel Int = Null
)
Returns Table
As
Return
With Ancestor As
(
Select @Path As Path
Union All
Select Path.GetAncestor(1)
From Ancestor
Where Path.GetLevel() > 0
)
Select Path, Path.GetLevel() As Level
From Ancestor
Where (@WithSelf = 1 Or Path <> @Path)
And Path.GetLevel() >= Case When @MinLevel < 0 Or @MinLevel Is Null Then 0 Else @MinLevel End
And (@MaxLevel Is Null Or Path.GetLevel() <= @MaxLevel)
要使用:
-- This assumes the table has a Path HierarchyId colum, and the values are unique and indexed.
-- If you know the path
Select *
From MyTable
Where Path In
(
Select Path From dbo.GetAllAncestors(@ThePath, Default, Default, Default)
)
-- If you don't know the path
Select *
From MyTable t1
Where Path In
(
Select Path
From MyTable t2
Cross Apply dbo.GetAllAncestors(t2.Path, Default, Default, Default)
Where /* Find the leaf record(s) here.
Note that if multiple rows match, they will all be returned as well as their parents in a single roundtrip. */
)
DECLARE @hid_Specific HIERARCHYID
SET @hid_Specific = '/1/1/3/1/';
SELECT hrchy_id,* FROM tblHierarchyData
WHERE PATINDEX(hrchy_id.ToString() + '%', @hid_Specific.ToString()) = 1