SQL处理多级分类,查询结果呈树形结构

with area as(
select *,id px,cast(id as nvarchar(4000)) px2 from region where parentid=0
union all
select a.*,b.px,b.px2+ltrim(a.region_id) from region a join area b on a.parentid=b.id
)select * from area order by px,px2

with area as(
select * from region where parentid=1
union all
select a.* from region a join area b on a.parentid=b.id
)select * from area