public ActionResult Index()
        {
            List <Currency> currency;

            using (Warehouse_DBEntities db = new Warehouse_DBEntities())
            {
                currency = db.Currency.ToList();
            }
            if (currency == null)
            {
                return(HttpNotFound());
            }
            ViewBag.Date = currency.FirstOrDefault().Date.ToString("d");
            return(View(currency));
        }