}
}
//------------------------ insert track ----------------------------//
if (isset($_POST['insert'])) {
    // first : check $_POST values
    //second : use values
    $track->name = $_POST['name'];
    $track->sup_id = $_POST['psup_id'];
    $track->no_course = $_POST['pno_course'];
    $track->no_stud = $_POST['no_stud'];
    $track->leader_id = $_POST['leader_id'];
    $track_id = $track->insert();
}
//------------------------ update track ----------------------------//
if (isset($GET['id'])) {
    if (!empty($_GET['id'])) {
        $data = $track->get_track($_GET['id']);
        //get all info about track want to update
    }
}
if (isset($_POST['update'])) {
    // first : check $_POST values
    //second : use values
    $track->id = $_GET['id'];
    $track->name = $_POST['name'];
    $track->sup_id = $_POST['psup_id'];
    $track->no_course = $_POST['pno_course'];
    $track->no_stud = $_POST['no_stud'];
    $track->leader_id = $_POST['leader_id'];
    $track->update();
}