SQL Server 树形表非循环递归查询的实例详解_Sql Server

SQL Server 树形表非循环递归查询的实例详解

2020-05-11 15:12小虾9527 Sql Server

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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：

SQL Server 树形表非循环递归查询的实例详解

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