public void UpdateInvoiceMenu(Invoice_Menu invoiceMenu)
 {
     context.Entry(invoiceMenu).State = EntityState.Modified;
 }
 public void InsertInvoiceMenu(Invoice_Menu invoiceMenu)
 {
     int id = context.Database.SqlQuery<int>("GetInvoiceMenuMaxID").Single() + 1;
     context.Invoice_Menu.Add(invoiceMenu);
 }