PHP 递归生成子级数据

public function doMobileWenzhang_cbt(){
    global $_GPC,$_W;

    $wzid=$_GPC['wzid'];

    $wzinfo=pdo_get('huoban_wenzhang',array('id'=>$wzid));

    //递归查询下级访问用户
    $list=pdo_fetchall("select * from ".tablename('huoban_readers')." where `zhuafanum`=1 and wzid={$wzid} ");

    foreach ($list as $k=>$v){
        $list[$k]['childs']=$this->cbt_dgsj($v['openid'],$v['wzid']);
    }

    echo "<pre/>";
    var_dump($list);die;

    echo json_encode(array('list'=>$list));

}

function cbt_dgsj($openid,$wzid){
    //echo "1<br/>";
    //echo "<pre/>";
    $xjlist=pdo_fetchall("select * from ".tablename('huoban_readers')." where fromuser='{$openid}' and wzid={$wzid} ");
    //var_dump($xjlist);
    if(!empty($xjlist)){

        foreach ($xjlist as $k=>$v){
            //var_dump($xjlist);
            $res=$this->cbt_dgsj($v['openid'],$v['wzid']);
            $xjlist[$k]['childs']=$res;
        }

        /*echo "1<br/><pre/>";
        var_dump($xjlist);*/
        return $xjlist;

    }

    //var_dump($list);die;
    return $xjlist;
}