PHP 数据库树的遍历方法

<?php
session_start();
define ('P_S', PATH_SEPARATOR);
define ('ROOT', "./");
set_include_path(ROOT .P_S .'Zend' .P_S .ROOT.get_include_path());
//加载ZEND 框架
require_once ROOT.'Zend/Loader.php';
require_once 'usercheck.php';//加载访问权限
Zend_Loader::loadFile('function.class.php', $dirs='class/', $once=false);//加载函数
Zend_Loader::loadClass('Zend_Db');//加载数据库类
Zend_Loader::loadClass('Zend_Config_Ini');//加载配置类
$config = new Zend_Config_Ini('config.php', 'general');//创建配置对象
$db = Zend_Db::factory($config->db->adapter,$config->db->config->toArray());//创建数据库对象
$select=$db->select();
$select->from('ResClass',array('lsh','name'));
$select->where('steps = 1');
$rs=$db->fetchAll($select);
foreach ($rs as $res){
echo '&nbsp;&nbsp;&nbsp;&nbsp;'.$res['lsh'].$res['name']."<br>";
Visit($res['lsh'],1);
}
function Visit($nodeid,$stept){
global $db;
$recordset = "SELECT lsh,name FROM ResClass WHERE parent=".$nodeid; //搜索nodeid的所有下层节点
$rs=$db->fetchAll($recordset);
foreach($rs as $rss){
if(!$rss)
return; //已经是叶子节点，直接返回
else{
for ($i=0;$i<4*$stept;$i++){
echo "&nbsp;";
}
echo '&nbsp;&nbsp;&nbsp;&nbsp;'.$rss['lsh'].$rss['name']."<br>";
Visit($rss['lsh'],$stept+1);
}
}
}
?>