AllDataDataContext locADC = new AllDataDataContext(Properties.Settings.Default.CurrentConnectionString);
 var querySumSale = from ag in locADC.Client where ag.ID == 1 select ag;

            foreach (var ca in querySumSale)
                Console.WriteLine(ca.SumSale.Value.ToString());
            
            locADC.SetSumSaleForClient(1,300);

            var querySumSale2 = from ag2 in locADC.Client where ag2.ID == 1 select ag2;

            foreach (var ca2 in querySumSale2)
                Console.WriteLine(ca2.SumSale.Value.ToString());

var querySumSale2 = from ag2 in locADC.Client where ag2.ID == 1 select ag2;

            foreach (var ca2 in querySumSale2)
                Console.WriteLine(ca2.SumSale.Value.ToString());