PHP实现无限分级

 1 <?php
 2 function tree($arr, $pid=0, $level=0){
 3     static $list = array();
 4     foreach($arr as $v){
 5         if($v['parent_id'] == $pid){
 6             $v['level'] = $level;
 7             $list[] = $v;
 8             tree($arr, $v['cat_id'], $level+1);
 9         }
10     }
11     return $list;
12 }
13 
14 $arr = array();
15 $conn = mysql_connect("localhost", "root", "");
16 mysql_select_db("test");
17 mysql_query("set names utf8");
18 $result = mysql_query("select * from category");
19 $i=0;
20 while($res = mysql_fetch_assoc($result)){
21     $arr[$i]['cat_id'] = $res['cat_id'];
22     $arr[$i]['cat_name'] = $res['cat_name'];
23     $arr[$i]['parent_id'] = $res['parent_id'];
24     $i = $i + 1;
25 }
26 $jieshu = tree($arr);
27 echo "<pre>";
28 print_r($jieshu);
29 echo "</pre>";
30 ?>