其他常见的无限分类方法：
1，简单的通过递归查询加目录path字段的无限分类
缺点：查询数据库次数太多，不方便其他操作，比如删除节点。添加节点，移动节点
2，左右值无限分类，预排序二叉树
缺点：操作繁琐，数据库冗余，且添加删除修改都要进行左右值更新
本分类方法的优势：
1，数据库结构简单，只有 cid parentid name 三个字段，无任何冗余字段
2，不使用递归查询，所有操作只需一条sql语句
3，所有数据在读取一次数据库后，在数组内进行分析处理，节省数据库服务器资源
创建数据库以及表：
CREATE DATABASE `sortclass`DEFAULT CHARSET utf8;
CREATE TABLE IF NOT EXISTS `class` (
`cid` mediumint(8) unsigned NOT NULL auto_increment,
`pid` mediumint(8) unsigned NOT NULL,
`cname` varchar(50) NOT NULL,
PRIMARY KEY (`cid`),
KEY `pid` (`pid`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
处理文件示例：
<?php
header("Content-type: text/html; charset=utf-8");
//连接数据库
$link = mysql_connect('localhost','root','eric') or die(mysql_error());
mysql_select_db('sortclass',$link);
//无限分类类库
class SortClass{
var $data = array();
var $child = array(-1=>array());
var $layer = array(-1=>-1);
var $parent = array();
var $link;
var $table;
function SortClass($link, $table){
$this->setNode(0, -1, '顶极节点');
$this->link = $link;
$this->table = $table;
$node = array();
$results = mysql_query('select * from '.$this->table.'',$this->link);
while($node = mysql_fetch_assoc($results)){
$this->setNode($node['cid'],$node['pid'],$node['cname']);
}
}
function setNode ($id, $parent, $value){
$parent = $parent?$parent:0;
$this->data[$id] = $value;
$this->child[$id] = array();
$this->child[$parent][] = $id;
$this->parent[$id] = $parent;
$this->layer[$id] = !isset($this->layer[$parent])? 0 : $this->layer[$parent] + 1;
}
function getList (&$tree, $root= 0){
foreach ($this->child[$root] as $key=>$id){
$tree[] = $id;
if ($this->child[$id]) $this->getList($tree, $id);
}
}
function getValue ($id){return $this->data[$id];}
function getLayer ($id, $space = false){
return $space?str_repeat($space, $this->layer[$id]):$this->layer[$id];
}
function getParent ($id){return $this->parent[$id];}
function getParents ($id){
while ($this->parent[$id] != -1){
$id = $parent[$this->layer[$id]] = $this->parent[$id];
}
ksort($parent);
reset($parent);
return $parent;
}
function getChild ($id){return $this->child[$id];}
function getChilds ($id = 0){
$child = array($id);
$this->getList($child, $id);
return $child;
}
function addNode($name,$pid){
mysql_query("insert into $this->table (`pid`,`cname`) values ('$pid','$name')",$this->link);
}
function modNode($cid, $newName){
mysql_query("update $this->table set `cname`='$newName' where `cid` = $cid",$this->link);
}
function delNode($cid){
$allChilds = $this->getChilds($cid);
$sql ='';
if(empty($allChilds)){
$sql = "delete from $this->table where `cid` = $cid";
}else{
$sql = 'delete from '.$this->table.' where `cid` in ('.implode(',',$allChilds).','.$cid.')';
}
mysql_query($sql,$this->link);
}
function moveNode($cid, $topid){
mysql_query("update $this->table set `pid`=$topid where `cid` = $cid", $this->link);
}
}
//函数
function back(){
echo '<script language="javascript">window.location.href="test.php?"+new Date().getTime();</script>';
exit;
}
//声成select
function makeSelect($array,$formName){
global $tree;
$select = '<select name="'.$formName.'">';
foreach ($array as $id){
$select.='<option value="'.$id.'">'.$tree->getLayer($id, '|-').$tree->getValue($id)."</option>";
}
return $select.'</select>';
}
$tree = new SortClass($link,'`class`');
$op = !empty($_POST['op']) ? $_POST['op'] : $_GET['op'];
if(!empty($op)){
if($op=='add'){
$tree->addNode($_POST['cname'],$_POST['pid']);
back();
}
if($op=='mod'){
$tree->modNode($_POST['cid'],$_POST['cname']);
back();
}
if($op=='del'){
$tree->delNode($_GET['cid']);
back();
}
if($op=='move'){
$tree->moveNode($_POST['who'],$_POST['to']);
back();
}
}
$category = $tree->getChilds();
?>
<style type="text/css">
body{font-size:12px;}
ul{list-style:none;}
a{cursor:pointer;}
</style>
<script language="javascript">
function $(e){return document.getElementById(e);}
function mod(cid){
$('cid').value=cid;
$('op').value='mod';
$('name').style.border='1px solid red';
}
</script>
<form action="test.php" method="post">
名称:<input type="text" id="name" name="cname" /> 添加到:<?=makeSelect($category,'pid')?><br />
<input type="hidden" id="op" name="op" value="add" />
<input type="hidden" id="cid" name="cid" />
<input type="submit" value="Submit" />
</form>
<h3>移动分类</h3>
<form action="test.php" method="post">
<?=makeSelect($category,'who')?>移动到:<?=makeSelect($category,'to')?>
<input type="hidden" id="op" name="op" value="move" />
<input type="submit" value="Submit" />
</form>
<ul>
<?php
foreach ($category as $id){
echo '<li>'.$tree->getLayer($id, '|－ ').$tree->getValue($id).' <a href="test.php?op=del&cid='.$id.'">Del</a> <a onclick="mod('.$id.')">Edit</a> </li>';
}
?>
</ul>