private void SynchronizeCustomers() { LastUpdate = new DateTime(1983, 11, 20); if (dataHandler.QueryCustomers().Count > 0) { LastUpdate = dataHandler.QueryCustomers().OrderByDescending(i => i.Modified).Select(j => j.Modified.GetValueOrDefault()).First(); } List <Customer> ServerCustomers = serviceHandler.CallService <List <Customer> >(@"QueryCustomers"); if (ServerCustomers != null) { List <Customer> newCustomers = ServerCustomers.Where(i => i.Modified > LastUpdate).Select(j => j).ToList(); foreach (var item in newCustomers) { if (dataHandler.QueryCustomers().Where(p => p.CustomerId.Equals(item.CustomerId)).Count() == 0) { dataHandler.InsertCustomer(item); } else { dataHandler.UpdateCustomer(item); } } } ; }