function checkIfAppointmentExistsApp($con)
{
    $sql = "SELECT * FROM appointments WHERE ID=" . $_GET['app'];
    $appointmentMatchWithId = pushQueryToArray($con, $sql);
    if (!empty($appointmentMatchWithId)) {
        return checkIfAppointmentBelongsToUser($con);
    } else {
        $_SESSION['errorDetailPage'] = "Deze afspraak bestaat niet, probeer het alstublieft opnieuw.";
        header('Location: ../pages/appointmentsoverview.php');
        die;
    }
}
function checkIfSetDelete($con)
{
    if (isset($_POST['delete'])) {
        checkIfAppointmentBelongsToUser($con);
    }
}