树节点查询

----------------建表-----------------------

 1 create table location
 2 (
 3 id bigint,
 4 pid bigint,
 5 name nvarchar(50)
 6 )
 7 go
 8 insert location
 9 select 001,0,'北京市'
10 union all
11 select 002,001,'海淀区'
12 union all
13 select 003,001,'朝阳区'
14 union all
15 select 004,0,'湖南省'
16 union all
17 select 005,004,'长沙市'
18 union all
19 select 006,004,'株洲市'
20 union all
21 select 007,0,'广东省'
22 union all
23 select 008,007,'广州市'
24 union all
25 select 009,007,'深圳市'
26 go
27 select * from location
28 go

--查询指定节点及其所有子节点的函数

 1 create function f_cid(@ID varchar(3)) returns @t_level table(id bigint , level int)
 2 as
 3 begin
 4   declare @level int
 5   set @level = 1
 6   insert into @t_level select @ID , @level
 7   while @@ROWCOUNT > 0
 8   begin
 9     set @level = @level + 1
10     insert into @t_level select a.id , @level
11     from location a , @t_Level b
12     where a.pid = b.id and b.level = @level - 1
13   end
14   return
15 end
16 go
17 select * from dbo.f_cid(007) as f 
18 inner join location as t
19 on f.id=t.id
20 go

--采用CTE,比如查询007下所有的子节点

 1 with t
 2 as
 3 (
 4     select id,pid,name from location
 5     where id=007
 6     union all
 7     select c.id,c.pid,c.name from location as c inner join t
 8     on c.pid=t.id
 9 )
10 select * from t

 --sql08 下有个新特性，我们可以应用 hierarchyid 类型

 1 CREATE TABLE locationWithHierarchyID
 2 (
 3     [Id] hierarchyid not null primary key,
 4     [Name] nvarchar(50) not null
 5 )
 6 GO
 7 
 8 INSERT INTO locationWithHierarchyID ([Id], [Name] )VALUES
 9     (hierarchyid::GetRoot(), '中国'),
10     ('/1/', '北京市'),
11     ('/1/1/', '海淀区'),
12     ('/1/2/', '朝阳区'),
13     ('/2/', '湖南省'),
14     ('/2/1/', '长沙市'),
15     ('/2/2/', '株洲市'),
16     ('/3/', '广东省'),
17     ('/3/1/', '广州市'),
18     ('/3/2/', '深证市')
19 GO
20 select * from locationWithHierarchyID
21 select Id.ToString() as path,Id.GetLevel() as level, Name  from locationWithHierarchyID
22 select * from locationWithHierarchyID
23 where Id.IsDescendantOf('/3/')=1