$id = $_GET['id'];
            $res = ActivityService::delete($id);
            header("Location: http://localhost/healthyone/view/activityManage.php");
        } else {
            if ($_GET['operation'] == 1) {
                $id = $_POST['id'];
                $describe = $_POST['describe'];
                $time = $_POST['time'];
                $place = $_POST['place'];
                $res = ActivityService::modify($id, $describe, $time, $place);
                header("Location: http://localhost/healthyone/view/activityManage.php");
            } else {
                if ($_GET['operation'] == 2) {
                    $id = $_POST['id'];
                    session_start();
                    $username = $_SESSION["username"];
                    $res = ActivityService::join($username, $id);
                    header("Location: http://localhost/healthyone/view/activity.php");
                } else {
                    if ($_GET['operation'] == 3) {
                        $id = $_POST['id'];
                        session_start();
                        $username = $_SESSION["username"];
                        $res = ActivityService::quit($username, $id);
                        header("Location: http://localhost/healthyone/view/myActivity.php");
                    }
                }
            }
        }
    }
}