/// <summary>
        /// Create detail of order.
        /// </summary>
        /// <param name="orderDetail">The object of detail that you want to create.</param>
        public void CreateOrderDetail(Guid OrderOfService_Id, Guid Service_Id, DateTime OrderOfServiceDetail_FromDate, DateTime OrderOfServiceDetail_ToDate, int OrderOfServiceDetail_NumberOfEmployee)
        {
            try
            {
                OrderOfServiceDetail oosd = OD.GetOrderDetail(OrderOfService_Id, Service_Id);
                if (oosd != null)
                    throw new Exception("Information of this order has been created.");
                OrderOfServiceDetail newOrderDetail = new OrderOfServiceDetail();
                newOrderDetail.OrderOfService_Id = OrderOfService_Id;
                newOrderDetail.OrderOfServiceDetail_FromDate = OrderOfServiceDetail_FromDate;
                newOrderDetail.OrderOfServiceDetail_NumberOfEmployee = OrderOfServiceDetail_NumberOfEmployee;
                newOrderDetail.OrderOfServiceDetail_ToDate = OrderOfServiceDetail_ToDate;
                newOrderDetail.Service_Id = Service_Id;

                int result = OD.CreateOrderDetail(newOrderDetail);
                if (result == -1)
                {
                    throw new Exception("An error occurred while executing this operation.");
                }
            }
            catch (Exception ex)
            {
                throw new Exception(ex.Message);
            }
        }
 /// <summary>
 /// Create detail of order.
 /// </summary>
 /// <param name="orderDetail">The object of detail that you want to create.</param>
 /// <returns>Return the number of rows affected or return -1 if occur exception.</returns>
 public int CreateOrderDetail(OrderOfServiceDetail orderDetail)
 {
     return DBHelper.Instance.Insert(orderDetail);
 }
 /// <summary>
 /// Update order detail's information.
 /// </summary>
 /// <param name="orderDetail">The order's detail be updated.</param>
 /// <returns>Return the number of rows affected or return -1 if occur exception.</returns>
 public int UpdateOrderDetail(OrderOfServiceDetail orderDetail)
 {
     return DBHelper.Instance.Update(orderDetail, String.Format("OrderOfService_Id = '{0}' AND Service_Id = '{1}'", orderDetail.OrderOfService_Id.ToString(), orderDetail.Service_Id.ToString()));
 }