<?php
$result = mysql_query ("SELECT `id`, `parent_id`, `name` FROM `category`");
$cats = array();
while($cat =  mysql_fetch_assoc($result))
    $cats[$cat['parent_id']][] =  $cat;
function create_tree ($cats,$parent_id){
    if(is_array($cats) and  isset($cats[$parent_id])){
        $tree = !$parent_id?'':'<ul>';
        foreach($cats[$parent_id] as $cat){
          $tree .= "<li>";
          $img = !$parent_id?'<img src="images/'.$cat['name'].'.png">':'';
          $tree .= !isset($cats[$cat['id']])?"<a href='view_cat.php?cat=".$cat['id']."'>".$img." ".$cat['name']."</a>":"<span>".$img." ".$cat['name']."</span>";
          $tree .=  create_tree($cats,$cat['id']);
          $tree .= '</li>';
        }
        $tree .= !$parent_id?'':'</ul>';
    }else return null;
return !$parent_id?'<ul class="sublist">'.$tree.'</ul>':$tree;
}
echo create_tree($cats, 0);
?>