根据 省市区层级关系将数据归纳整理，题目如下

答：可以按照省市区三级查询临时表，然后根据parentid将3张临时表关联。

方法一：

select * into #a1 from DuoJi where ParentId=0
select * into #a2 from DuoJi where ParentId in (select id from #a1)
select * into #a3 from DuoJi where ParentId in (select id from #a2)

select a1.Name as '一级地名',a2.Name as '二级地名',a3.Name as '三级地名' from #a3 a3 inner join #a2 a2 on a3.ParentId=a2.Id inner join #a1 a1 on a2.ParentId=a1.Id

方法二：

select faddr.name '一级地名',saddr.name '二级地名',taddr.name '三级地名' from address a 
join (SELECT id,name,parent_id from address) faddr on a.id=faddr.id
                        join (SELECT id,name,parent_id from address) saddr on faddr.id=saddr.parent_id
                        join (SELECT id,name,parent_id from address) taddr on saddr.id=taddr.parent_id