SQl树查询

一、SqlServer树查询

1、使用公用表表达式（CTE）

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 table

    Where id = 6  -- 要查询的子 id 

    Union All

    Select table.* From table, Tree

    Where Tree.parent = table.id

) 

Select * From Tree;



--通过父节点查询子节点

With Tree As(

    Select * From table

    Where parent = 2  -- 要查询的父 id 

    Union All

    Select table.* From table, Tree

    Where table.parent = Tree.id

) 

Select * From Tree;

 2、自定义函数方式：

Create Function dbo.GetSubtreeInfo ( @parentId AS nvarchar(20) ) 

Returns @treeinfo table 

(   FunctionId nvarchar(20) NOT NULL , 

    FunctionName nvarchar(50) NOT NULL, 

    Url nvarchar(100), 

    ParentId nvarchar(20) NOT NULL, 

    OrderId nvarchar(20),

    [levels] [int] NOT NULL 

) 

As

Begin 


Declare @level As int 

Select @level = 0 

Insert Into @treeinfo 

    Select FunctionId, FunctionName, Url, ParentId, OrderId, @level 

    From SystemFunction 

    Where ParentId  = @parentId 

While @@ROWCOUNT > 0 

Begin 



Set @level = @level + 1 

Insert Into @treeinfo 

    Select E.FunctionId, E.FunctionName, E.Url, E.ParentId, E.OrderId, @level 

    From SystemFunction as E JOIN @treeinfo as T 

    On E.ParentId = T.FunctionId and T.levels = @level - 1 



End 

Return 

End 

drop function dbo.GetSubtreeInfo 

select * from dbo.GetSubtreeInfo('F0000')