SQL Server 树形表非循环递归查询的实例详解

2020-07-25 12:43:58

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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_GetAreaStrgocreate procedure SP_GetAreaStr @id intasdeclare @area varchar(8000)beginWITH 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= @areaend go--exec sp_helptext 'SP_GetAreaStr'--goexec SP_GetAreaStr 28go

查询结果：中国安徽省宿州市灵璧县

所用表结构：