在与同事Rock讨论中，得到一个思路，不用嵌套调用直接用一个语句就可以生成树，实事上他已经做好了该程序，他用了临时表写了一个存储过程，我改写为一个表值函数，供大家参考：
在与同事Rock讨论中，得到一个思路，不用嵌套调用直接用一个语句就可以生成树，实事上他已经做好了该程序，他用了临时表写了一个存储过程，我改写为一个表值函数，供大家参考：
表结构及表值函数如下：
查询树表语句
1/**//****** Object: Table [dbo].[Tree] Script Date: 2005-11-04 18:07:00 ******/
2
CREATE TABLE [dbo].[Tree] (
3 [ID] [int] IDENTITY (1, 1) NOT NULL ,
4 [PID] [int] NULL ,
5 [Name] [varchar] (10) COLLATE Chinese_PRC_CI_AS NULL
6) ON [PRIMARY]
7GO
8
9 CREATE CLUSTERED INDEX [IX_Tree] ON [dbo].[Tree]([PID]) ON [PRIMARY]
10GO
11
12ALTER TABLE [dbo].[Tree] WITH NOCHECK ADD
13 CONSTRAINT [PK_Tree] PRIMARY KEY NONCLUSTERED
14 (
15 [ID]
16 ) ON [PRIMARY] ,
17 CONSTRAINT [子ID不能等于父ID] CHECK ([ID] <> [PID])
18GO
19
20ALTER TABLE [dbo].[Tree] ADD
21 CONSTRAINT [FK_Tree_Tree] FOREIGN KEY
22 (
23 [PID]
24 ) REFERENCES [dbo].[Tree] (
25 [ID]
26 )
27GO
28
29/**//****** 对象: 用户定义的函数 dbo.fGetTreeTable 脚本日期: 2005-11-04 18:07:02 ******/
30CREATE FUNCTION dbo.fGetTreeTable
31 (
32 @ID int= null
33 )
34RETURNS @Tab TABLE(ID int, PID int, Name varchar(10), Lev int)
35AS
36 BEGIN
37 Declare @lev int
38 Set @lev=0
39
40 While @lev=0 or @@ROWCount>0
41 Begin
42 Set @Lev=@Lev+1
43 Insert @Tab(ID, PID, Name, Lev)
44 Select ID, PID, Name, @Lev From Tree Where (@Lev=1 and ((PID=@ID) or (@ID is null and PID is null))) or (PID in (Select ID From @Tab Where Lev=@Lev-1))
45 order by ID
46 End
47 RETURN
48 END
49
50GO
51
52--实际数据
53Insert Tree(PID, Name) values(null, 公司)
54Insert Tree(PID, Name) values(3, IT)
55Insert Tree(PID, Name) values(1, Fin)
56Insert Tree(PID, Name) values(5, XZ)
57Insert Tree(PID, Name) values(1, HR)
58GO
59
60直接查询Select * from dbo.fGetTreeTable(null)就可以输入所有记录。
