static void Main(string[] args)
{
CustomerManager customerManager = new CustomerManager();
customerManager.add();
customerManager.update();
ProductManager product = new ProductManager();
product.add();
product.update();
Customer customer = new Customer();
customer.customerInfo();
customer.firstName = "Enis";
customer.lastName = "Çeri";
customer.city = "İstanbul";
customer.id = 12;
customer.customerInfo();
Console.Read();
}