static void Main(string[] args)
        {
            OracleCustomerDal.CustomerManager customerManager = new OracleCustomerDal.CustomerManager();
            // demo(customerManager);
            ICustomerDal[] customerDals = new ICustomerDal[3]
            {
                new SqlServerCustomerDal(),
                new OracleCustomerDal(),
                new OracleCustomerDal.MysqlServerCustomerDal(),
            };

            foreach (var customerDal in customerDals)
            {
                customerDal.Add();
            }

            Console.ReadLine();
        }
 private static void demo(OracleCustomerDal.CustomerManager customerManager)
 {
     customerManager.Add(new OracleCustomerDal());    // interface'den çekilen class özellikleri.
     customerManager.Add(new SqlServerCustomerDal()); // interface'den çekilen class özellikleri.
 }