SQL Server 树形表非循环递归查询的实例详解
很多人可能想要查询整个树形表关联的内容都会通过循环递归来查…事实上在微软在SQL2005或以上版本就能用别的语法进行查询，下面是示例。
–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查询结果为：
修改代码为
–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
则结果为：中国北京市丰台区
根据以上可以将这段代码封装为一个存储过程
—–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
查询结果：中国安徽省宿州市灵璧县
所用表结构：
部分数据：
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