根据分类ID获得所有子ID和所有父ID

数据表

ID	Name		Parent_ID
1	计算机		NULL
2	联想计算机	1
3	戴尔计算机	1
6	手机		NULL
7	诺基亚手机	6
8	苹果手机		6
9	HTC手机		6
10	工程采购		NULL
11	建筑工程		10
12	房产采购		10
13	联想悦动		2

-- 根据ID获得它下面的所有子分类

create function UF_GetChildMaterialCategories( @Id int )
returns  @tb table (ID int)
as
begin
insert into @tb
select ID from MaterialCategories where Parent_ID = @Id
while @@Rowcount >0  --只要有下级节点就循环
begin
insert into @tb
select a.ID  from MaterialCategories as a inner join @tb as b on a.Parent_ID = b.id and a.id not in(select id from @tb)
end
return
end
go

--执行
select * from  UF_GetChildMaterialCategories(1)

--根据传入的分类ID，返回它的上级分类。

create function UF_GetParentMaterialCategories( @Id int )
returns  @tb table (id int)
as
begin
insert into @tb
select parent_id from MaterialCategories where id = @Id
while @@Rowcount >0
begin
insert into @tb
select a.parent_id
from MaterialCategories as a inner join @tb as b on a.id = b.id and a.parent_id not in(select id from @tb)
end
return
end
go

--执行

select * from UF_GetParentMaterialCategories(13)