/// <summary>
/// 取得 Orders by 條件
/// </summary>
/// <returns></returns>
public IList <Order> GetOrders(OrderQueryArg arg)
{
CustomerService customerService = new CustomerService();
OrdersDao orderDao = new OrdersDao();
// 取得所有訂單後進行篩選 (注意: 此處應將查詢條件串入SQL中為較好之寫法)
IEnumerable <Order> currentOrders = orderDao.GetOrdersByArg(arg);
return(currentOrders.OrderBy(m => m.OrderID).ToList());
}