循环查询sql server（SQL Server 树形表非循环递归查询的实例详解）

--通过子节点查询父节点
WITH 
TREE AS( 
SELECT * FROM Areas 
WHERE id = 6 -- 要查询的子 id 
UNION ALL 
SELECT Areas.* FROM Areas, TREE 
WHERE TREE.PId = Areas.Id
) 
SELECT Area FROM TREE
--通过父节点查询子节点
WITH 
TREE AS( 
SELECT * FROM Areas 
WHERE id = 7 -- 要查询的子 id 
UNION ALL 
SELECT Areas.* FROM Areas, TREE 
WHERE TREE.Id = Areas.PId
) 
SELECT Area FROM TREE

--通过子节点查询父节点
declare @area varchar(8000);
WITH 
TREE AS( 
SELECT * FROM Areas 
WHERE id = 6 -- 要查询的子 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

-----存储过程，递归获取树形地区表字符串
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 -- 要查询的子 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