passing a mysqli object via globals

warn: already posted in general.... with no response... maybe is too basic.. but I RTFM and still is not clear to me what I am doing wrong.... I want to open a database connection at program initialization and use that very same connection via globals initilizating ( loading from db) other objects. Basically index.php require_once ('file.php'); $db=new mysqli(host,us,pass,db); if(mysqli_connect_errno()){

    die('errordb conex');

} switch ($var){

    display1:
        $obj=new obj_x();
        $obj->load();
        $obj->display();
        break;
    display2:
        $obj=new obj_y();
        $obj->load();
        $obj->display();
        break;

} ------------------ class file.php class obj_x{

    function load(){
        globals $db;

        $sql="select ....);
        $ret=$db->query($sql); // XX
        ...
        }

} fails at XX with Warning: mysqli::query() [function.mysqli-query]: Couldn't fetch mysqli in class file .... line XX Any hints ??. I am using php 5.1.6 with linux/ubuntu. Thanks. JCG