• SQLServer 之 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')
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  • 原文地址:https://www.cnblogs.com/xinaixia/p/4015014.html
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