请教这条Sql语句如何写

请问这条Sql语句怎么写？
ProductClass表结构：ClassId,ClassName,ParentClassId
要查询一个ClassID 下所有的字 类别，Sql语句怎么写？


[解决办法]

SQL code

select    a.name as column_name,    b.name as date_typefrom    syscolumns ajoin    systypes b    on a.xusertype=b.xusertypewhere a.id=object_id('ProductClass')
[解决办法]
如果只是classid下面一级,就很简单,如果是n级,

1个sql语句是无法解决问题的,可能需要配合其它的才能实现
[解决办法]
SQL code
create table os(id int,parentid int,desn varchar(10))insert into os select 1,0,'体育用品'insert into os select 2,0,'户外运动'insert into os select 3,1,'篮球'insert into os select 4,1,'足球'insert into os select 5,2,'帐篷'insert into os select 6,2,'登山鞋'insert into os select 7,0,'男士用品'insert into os select 8,7,'刮胡刀'insert into os select 9,3,'大号篮球'--首先查找该节点下所有子接点create function f_cid(@id int)returns @t table(id int,parentid int,desn varchar(10),lev int)asbegin     declare @lev int     set @lev=1     insert into @t select *,@lev from  os where id=@id     while(@@rowcount>0)     begin          set @lev=@lev+1          insert into @t select a.*,@lev from os a,@t b          where a.parentid=b.id and b.lev=@lev-1     end     returnend--调用:select * from dbo.f_cid(1)