$id             = trim($_GET['id']);
    $check_activity = $mysqli->query("SELECT serie, titulo, episodio, temporada, image, url, fecha FROM actividad WHERE user_id = '".$id."' ");
    /* si hay data cambiamos $act */
    if($check_activity->num_rows > 0){
        $act = array();
        while($ac = $mysqli->fetch_assoc($check_activity)) {
            $act[] = $ac;
    }