php+mysql简单的无限分类栏目

$sql = 'select * from cat order by cat_id desc';
$list = $db->getAll($sql);
$list = getLevelCat($list);
function getLevelCat($catlist, $parent_id='0', $html='   ', $level='0'){
    $arr = array();
    foreach($catlist as $val){
        if($val['parent_id']==$parent_id){
            $val['html'] = str_repeat($html,$level);
            $val['level'] = $level;
            $arr[] = $val;
            $arr = array_merge($arr, getLevelCat($catlist, $val['cat_id'], $html, $level+1));
        }
    }
    return $arr;
}