public void Add( string ClientName, string Address, string PhoneNumber, string Tariff, string Zone, string PonClient, string Comment) { BillingSystemContext context = new BillingSystemContext(); int zone = context.Zones.FirstOrDefault(z => z.Town == Zone).IDNumber; int tariff = context.Tariffs.FirstOrDefault(t => t.Name == Tariff).IDNumber; Client client = new Client() { Name = ClientName, Adress = Address, ZoneId = zone, IPAdress = null, PhoneNumber = PhoneNumber, Comment = Comment, Included = DateTime.Now, Validity = DateTime.Now, TariffId = tariff }; ClientsDao dao = new ClientsDao(); dao.Insert(client); }