tring querry = "Select distinct [Customer] from [CustDeptStore]";
SqlCommand cmd1 = new SqlCommand(querry, conn1);
SqlDataReader dr = cmd.ExecuteReader();
txtval3.AutoCompleteMode = AutoCompleteMode.Append;
txtval3.AutoCompleteSource = AutoCompleteSource.CustomSource;
txtval3.AutoCompleteCustomSource = namesCollection;