function generate_department_id()
{
    include 'db_auth.php';
    $department_id = "DEPARTMENT_" . rand(0, 999);
    $existing_ids = mysqli_num_rows(mysqli_query($conn, "select `departments`.`department_id` from `departments` where `departments`.`department_id`='{$department_id}'"));
    switch ($existing_ids) {
        case 0:
            return $department_id;
            break;
        default:
            generate_faculty_id();
    }
}
function generate_faculty_id()
{
    include 'db_auth.php';
    $faculty_id = "FACULTY_" . rand(0, 999);
    $existing_ids = mysqli_num_rows(mysqli_query($conn, "select `faculty`.`faculty_id` from `faculty` where `faculty`.`faculty_id`='{$faculty_id}'"));
    switch ($existing_ids) {
        case 0:
            return $faculty_id;
            break;
        default:
            generate_faculty_id();
    }
}