PHP Infinitus-Klassifizierungsmethode

<?php
$conn = mysql_connect("localhost","admin","admin");
mysql_select_db("people_shop",$conn);
mysql_query("SET NAMES &#39;UTF-8&#39;");
$class_arr=array();
$sql = "select * from ecs_brand ORDER BY brand_id asc ";
$query = mysql_query($sql);
while($row = mysql_fetch_array($query)){
  $class_arr[] = array($row[&#39;brand_id&#39;],$row[&#39;brand_name&#39;],$row[&#39;parent_id&#39;],$row[&#39;sort_order&#39;]);
}
function dafenglei_select($m,$id,$index)
{  
  global $class_arr;
  global $str;
  $n = str_repeat("    ",$m);
  // $n = $m;
  for($i=0;$i<count($class_arr);$i++){
    if($class_arr[$i][&#39;2&#39;]==$id){
      if($class_arr[$i][&#39;0&#39;]==$index){
        $str.= "<option value=\"".$class_arr[$i][0]."\" selected=\"selected\">".$n.$class_arr[$i][1]."</option>\n";
      }else{
        $str.= "<option value=\"  ".$class_arr[$i][0]."\">".$n.$class_arr[$i][1]."</option>\n";
      }
      dafenglei_select($m+1,$class_arr[$i][0],$index);    
    }
  }
  return $str;
}
$aa = dafenglei_select(1,0,0);
?>
<select name="parent_id">
<option value=&#39;0&#39;>顶级分类</option>
<?php
 echo $aa;
?>
</select>

<select name="parent_id">
<option value=&#39;0&#39;>顶级分类</option>
{$wuxian_class}
</select>

function dafenglei_select(& $arr=array(),$m,$id,$index)
{  
  // global $class_arr;
  global $str;
   $n = str_repeat("    ",$m);
  // $n = $m;
  for($i=0;$i<count($arr);$i++){
    if($arr[$i][&#39;2&#39;]==$id){
      if($arr[$i][&#39;0&#39;]==$index){
        $str.= "<option value=\"".$arr[$i][0]."\" selected=\"selected\">".$n.$arr[$i][1]."</option>\n";
      }else{
        $str.= "<option value=\"  ".$arr[$i][0]."\">".$n.$arr[$i][1]."</option>\n";
      }
      dafenglei_select($arr,$m+1,$arr[$i][0],$index);
    }
  }
   return $str;
}