private void setService(int service_id,  int service_time, int driver_id, int bus_id, Date weekStart)
  {
    if (weekStart == null) throw new InvalidQueryException("Date is null");
    if (service_time == 0) throw new InvalidQueryException("Time is null");
    if (service_id == 0) throw new InvalidQueryException("Nonexistent service");
    if (driver_id == 0) throw new InvalidQueryException("Nonexistent driver");
    if (bus_id == 0) throw new InvalidQueryException("Nonexistent bus");

    database.busDatabase.new_record("roster", new Object[][]{{"service_id", service_id}, {"service_time", service_time}, {"driver_id", driver_id}, {"bus_id", bus_id}, {"weekStart", weekStart}});
  }