三种实现方法实现数据表中遍历寻找子节点(页 1) - 软件学习交流

star2008 发表于 2008-5-16 08:21

三种实现方法实现数据表中遍历寻找子节点

数据表中遍历寻找子节点的三种实现方法：
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示例问题如下： r Fi4SC

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表结构:
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Id ParentId L}+nD'V1U&]UK{k

1 0 Z'n s)L3H Y5a#s,[J
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2 1 +w:i~T;VI\l&t6_;O
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3 2 si7qBi1S
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...... ;W@ ~-A4XM(Li

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针对该表结构解释如下:

1的父节点为0,
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2的父节点为1, 1s n"a.` Wm(q

3的父节点为2 8kY.b^R.d&F4~I]
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以此类推,要求给定一个父节点的值,比如1,
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用SQL语句查询的到该父结点下的所有子节点 'm4N3D b5G

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下面的Sql是在Sql Server下调试通过的,如果是Oracle,则有Connect By可以实现.

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建立测试表:
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Drop Table DbTree
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Create Table DbTree 5LZU:b L[
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[Id] Int, #D@Gc4YU/qr4N E

[Name] NVarChar(20), r/o0Bl#E)S'^

[ParentId] Int
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插入测试数据: 5^'y?ul u?
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Insert Into DbTree ([Id],[ParentId]) Values (1,0)

Insert Into DbTree ([Id],[ParentId]) Values (2,1)
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Insert Into DbTree ([Id],[ParentId]) Values (3,1)
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Insert Into DbTree ([Id],[ParentId]) Values (4,3)

Insert Into DbTree ([Id],[ParentId]) Values (5,4) !JJ'{_ s7s"\'I:T.j
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Insert Into DbTree ([Id],[ParentId]) Values (6,7)

Insert Into DbTree ([Id],[ParentId]) Values (8,5) Vk^One

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实现方法一: 0]bK ?k J

代码如下:

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Declare @Id Int

Set @Id = 1 ---在次修改父节点

Select * Into #Temp From DbTree Where ParentId In (@Id)
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Select * Into #AllRow From DbTree Where ParentId In (@Id) --1,2

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While Exists(Select * From #Temp)

Begin Q,d#J Td5`!B(p
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Select * Into #Temp2 From #Temp
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Truncate Table #Temp r8?!Y)s,Vo:Z
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Insert Into #Temp Select * From DbTree Where ParentId In (Select Id From #Temp2) j4x5^)~!Qur
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Insert Into #AllRow Select * From #Temp P `[$v/D,p
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Drop Table #Temp2
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End
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Select * From #AllRow Order By Id mJae0}*s'DjF.o

Drop Table #Temp #t,["J/gD

Drop Table #AllRow

star2008 发表于 2008-5-16 08:21

实现方法二: (E9b)i4eV$MFX UT W
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代码如下:
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Create Table #AllRow
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Id Int, T7r8sePsf$x3FHW

ParentId Int
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Declare @Id Int 5U5U7S?2`G:\x1mkY
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Set @Id = 1 ---在次修改父节点

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Delete #AllRow +_n*Qe,LA*E
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--顶层自身

Insert Into #AllRow (Id,ParentId) Select @Id, @Id
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Begin

Insert Into #AllRow (Id,ParentId) 9P S/F5[/}u/x.P

Select B.Id,A.Id ,? ciHp$K*I
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From #AllRow A,DbTree B ;o U4G*t2R

Where A.Id = B.ParentId And

Not Exists (Select Id From #AllRow Where Id = B.Id And ParentId = A.Id)

End

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Delete From #AllRow Where Id = @Id

Select * From #AllRow Order By Id K6W-H!D AOP
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Drop Table #AllRow

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实现方法三: RM#WTJ]S

代码如下:

在Sql Server2005中其实提供了CTE[公共表表达式]来实现递归:
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关于CTE的使用请查MSDN

Declare @Id Int $@P%P BkN

Set @Id = 3; ---在次修改父节点 Ie^(pi9s:M3?

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With RootNodeCTE(Id,ParentId) #N6w8VBF'wpS"|

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Select Id,ParentId From DbTree Where ParentId In (@Id)
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Select DbTree.Id,DbTree.ParentId From RootNodeCTE t8_xC FZ"b
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Inner Join DbTree
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On RootNodeCTE.Id = DbTree.ParentId nlUe]"m*N

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Select * From RootNodeCTE

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三种实现方法实现数据表中遍历寻找子节点