php 无限分类解决方案

function sort1($id,$number)
{
        global $conn;
        for($i=0;$i<$number;$i++) {
          $nbsp.= '&nbsp;&nbsp;&nbsp;';
        }
        $sql = mysql_query("select * from `sort` where fid=".$id."",$conn);
        while ($info=mysql_fetch_array($sql)) {
            //echo "循环变量i的数值：".$i."<br/>";
            echo $nbsp.'<option value=" '.$info["id"].'" >'.$nbsp.'┠'.$info["fname"].'</option>';
            $sql1 = mysql_query("select * from sort where fid=".$info["id"]."",$conn);
            if ($arr = mysql_fetch_array($sql1)) {
                echo sort1($info["id"],$number+1);
            }
        }
}

function sort1($id,$number)
{
    global $conn;
            for($i=0;$i<$number;$i++) {
              $nbsp.= '&nbsp;&nbsp;&nbsp;';
            }
    $sql=mysql_query("select * from `sort` where fid=".$id."",$conn);
    $total=mysql_num_rows($sql);
    $i=0;
    do{
    $i++; 
    //echo "循环变量i的数值：".$i."<br/>";
    $info=mysql_fetch_array($sql);
    echo $nbsp.'名字：【'.$info["fname"].'】id号：【'.$info["id"].'】fid号：【'.$info["fid"].'】<br/>';
    $sql1=mysql_query("select count(*) as total from sort where fid=".$info["id"]."",$conn);
    $arr=mysql_fetch_array($sql1);
    $sum=$arr["total"];
     if($sum>0){
      echo sort1($info["id"],$number+1); 
     }
    }while($i<$total);
}
<form method="post" action="sort.php">
<select name="sortid">
      <option value="0">-- 顶级分类 --</option>
      <?php echo sort1(0,0); ?>
    </select><br/>
    分类名<input name="sortname" type="text" size="20" />

    <input type="submit" name="button" id="button" value="添加" />
</form>