SQL Server 树形表非循环递归查询

SQL Server 树形表非循环递归查询

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：