在我的应用程序中，用户启动一棵新树或添加到子用户下并继续以这种方式在分支中添加用户->树类型结构有 10 级。
@ 987654322@root 节点包含 1 用户，每个节点（用户）可以有 max 5 child-user 这样树就会像 level 0 = 1 user ,level 1 = 5 user,level 2 = 25 user ,level 3 = 125 user 等等。
我创建了一个 MySQL 表，其列如下-
User_id、level、super_id、child1_id、child2_id、child3_id、child4_id、child5_id
我的问题是如何获取任何级别的特定用户的所有子用户(child to child also)我需要在表中添加更多列吗？？
【问题讨论】：
标签： php data-structures hierarchical-data
您可能会觉得阅读我上周 PHP TEK-X 会议上的演讲会很有趣：
本演讲描述了 SQL 中的替代解决方案，包括：
另请参阅我对 Stack Overflow 问题的回答：What is the most efficient/elegant way to parse a flat table into a tree?
【讨论】：
你应该看看Nested Sets。
在 PHP 中，您可以使用Doctrine Nested Sets，这将使您的生活更轻松。
【讨论】：
这是我用来构建二叉树数据结构及其相应操作的完整代码：
<?php
class Node
{
public $data;
public $leftChild;
public $rightChild;
public function __construct($data)
{
$this->data=$data;
$this->leftChild=null;
$this->rightChild=null;
}
public function disp_data()
{
echo $this->data;
}
}//end class Node
class BinaryTree
{
public $root;
//public $s;
public function __construct()
{
$this->root=null;
//$this->s=file_get_contents('store');
}
//function to display the tree
public function display()
{
$this->display_tree($this->root);
}
public function display_tree($local_root)
{
if($local_root==null)
return;
$this->display_tree($local_root->leftChild);
echo $local_root->data."<br/>";
$this->display_tree($local_root->rightChild);
}
// function to insert a new node
public function insert($key)
{
$newnode=new Node($key);
if($this->root==null)
{
$this->root=$newnode;
return;
}
else
{
$parent=$this->root;
$current=$this->root;
while(true)
{
$parent=$current;
//$this->find_order($key,$current->data);
if($key==($this->find_order($key,$current->data)))
{
$current=$current->leftChild;
if($current==null)
{
$parent->leftChild=$newnode;
return;
}//end if2
}//end if1
else
{
$current=$current->rightChild;
if($current==null)
{
$parent->rightChild=$newnode;
return;
} //end if1
} //end else
}//end while loop
}//end else
} //end insert function
//function to search a particular Node
public function find($key)
{
$current=$this->root;
while($current->data!=$key)
{
if($key==$this->find_order($key,$current->data))
{
$current=$current->leftChild;
}
else
{
$current=$current->rightChild;
}
if($current==null)
return(null);
}
return($current->data);
}// end the function to search
public function delete1($key)
{
$current=$this->root;
$parent=$this->root;
$isLeftChild=true;
while($current->data!=$key)
{
$parent=$current;
if($key==($this->find_order($key,$current->data)))
{
$current=$current->leftChild;
$isLeftChild=true;
}
else
{
$current=$current->rightChild;
$isLeftChild=false;
}
if($current==null)
return(null);
}//end while loop
echo "<br/><br/>Node to delete:".$current->data;
//to delete a leaf node
if($current->leftChild==null&&$current->rightChild==null)
{
if($current==$this->root)
$this->root=null;
else if($isLeftChild==true)
{
$parent->leftChild=null;
}
else
{
$parent->rightChild=null;
}
return($current);
}//end if1
//to delete a node having a leftChild
else if($current->rightChild==null)
{
if($current==$this->root)
$this->root=$current->leftChild;
else if($isLeftChild==true)
{
$parent->leftChild=$current->leftChild;
}
else
{
$parent->rightChild=$current->leftChild;
}
return($current);
}//end else if1
//to delete a node having a rightChild
else if($current->leftChild==null)
{
if($current==$this->root)
$this->root=$current->rightChild;
else if($isLeftChild==true)
{
$parent->leftChild=$current->rightChild;
}
else
{
$parent->rightChild=$current->rightChild;
}
return($current);
}
//to delete a node having both childs
else
{
$successor=$this->get_successor($current);
if($current==$this->root)
{
$this->root=$successor;
}
else if($isLeftChild==true)
{
$parent->leftChild=$successor;
}
else
{
$parent->rightChild=$successor;
}
$successor->leftChild=$current->leftChild;
return($current);
}
}//end the function to delete a node
//Function to find the successor node
public function get_successor($delNode)
{
$succParent=$delNode;
$successor=$delNode;
$temp=$delNode->rightChild;
while($temp!=null)
{
$succParent=$successor;
$successor=$temp;
$temp=$temp->leftChild;
}
if($successor!=$delNode->rightChild)
{
$succParent->leftChild=$successor->rightChild;
$successor->rightChild=$delNode->rightChild;
}
return($successor);
}
//function to find the order of two strings
public function find_order($str1,$str2)
{
$str1=strtolower($str1);
$str2=strtolower($str2);
$i=0;
$j=0;
$p1=$str1[i];
$p2=$str2[j];
while(true)
{
if(ord($p1)<ord($p2)||($p1==''&&$p2==''))
{
return($str1);
}
else
{
if(ord($p1)==ord($p2))
{
$p1=$str1[++$i];
$p2=$str2[++$j];
continue;
}
return($str2);
}
}//end while
} //end function find string order
public function is_empty()
{
if($this->root==null)
return(true);
else
return(false);
}
}//end class BinaryTree
?>
【讨论】：