--通過子節(jié)點查詢父節(jié)點
WITH 
TREE AS( 
SELECT * FROM Areas 
WHERE id = 6 -- 要查詢的子 id 
UNION ALL 
SELECT Areas.* FROM Areas, TREE 
WHERE TREE.PId = Areas.Id
) 
SELECT Area FROM TREE
--通過父節(jié)點查詢子節(jié)點
WITH 
TREE AS( 
SELECT * FROM Areas 
WHERE id = 7 -- 要查詢的子 id 
UNION ALL 
SELECT Areas.* FROM Areas, TREE 
WHERE TREE.Id = Areas.PId
) 
SELECT Area FROM TREE

通過子節(jié)點查詢父節(jié)點查詢結(jié)果為：

修改代碼為

--通過子節(jié)點查詢父節(jié)點
declare @area varchar(8000);
WITH 
TREE AS( 
SELECT * FROM Areas 
WHERE id = 6 -- 要查詢的子 id 
UNION ALL 
SELECT Areas.* FROM Areas, TREE 
WHERE TREE.PId = Areas.Id
)
select @area=isnull(@area,'')+Area from Tree order by id 
select Area= @area

則結(jié)果為：中國北京市豐臺區(qū)

根據(jù)以上可以將這段代碼封裝為一個存儲過程

-----存儲過程，遞歸獲取樹形地區(qū)表字符串
if exists (select * from sysobjects where name='SP_GetAreaStr')
drop proc SP_GetAreaStr
go
create procedure SP_GetAreaStr 
@id int
as
declare @area varchar(8000)
begin
WITH 
TREE AS( 
SELECT * FROM Areas 
WHERE id = @id -- 要查詢的子 id 
UNION ALL 
SELECT Areas.* FROM Areas, TREE 
WHERE TREE.PId = Areas.Id
)
select @area=isnull(@area,'')+Area from Tree order by id 
select Area= @area
end 
go
--exec sp_helptext 'SP_GetAreaStr'
--go
exec SP_GetAreaStr 28
go

查詢結(jié)果：中國安徽省宿州市靈璧縣

所用表結(jié)構(gòu)：