public bool Save()
        {
            bool flag = false;

            if (command == "UPDATE")
            {
                flag = new InvoiceBizDAO().UpdateInvoice(this);
            }
            else
            {
                flag = new InvoiceBizDAO().InsertInvoice(this);
            }

            return(flag);
        }
        public List <Invoice> ViewInvoices(string billingID, string orderID)
        {
            var invoiceList = new InvoiceBizDAO().ViewInvoices(billingID, orderID);

            return(invoiceList);
        }
        public List <Invoice> GetInvoiceID(string invoiceID)
        {
            var invoiceList = new InvoiceBizDAO().GetInvoiceID(invoiceID);

            return(invoiceList);
        }
        public Invoice GetById(string billingID, string orderID)
        {
            var invoices = new InvoiceBizDAO().GetInvoices(invoiceID, orderID);

            return(invoices[0]);
        }