public static void Test_Config_File()
        {
            // use the demo to use App.config file to get connstr and customized variable value
            string connectionString = ConfigurationManager.ConnectionStrings["SQL_Connection"].ConnectionString;

            Console.WriteLine("C4_Listing29_30, ConnStr is:{0}", connectionString);

            string Setting_Value = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None).AppSettings.Settings["Setting1"].Value.ToString();

            Console.WriteLine("C4_Listing29_30, Setting1 is:{0}", Setting_Value);
            C4_Listing27.Test_SqlConnection(connectionString);
        }
        public static void Test_SqlConnStrBuilder()
        {
            var sqlConnectionStringBuilder = new SqlConnectionStringBuilder();

            sqlConnectionStringBuilder.DataSource         = @"HUICHEN";
            sqlConnectionStringBuilder.InitialCatalog     = "Hui";
            sqlConnectionStringBuilder.IntegratedSecurity = true;

            string connectionString = sqlConnectionStringBuilder.ToString();

            Console.WriteLine("C4_Listing28, ConnStr is:{0}", connectionString);

            C4_Listing27.Test_SqlConnection(connectionString);
        }