//Function: update the DeliveryState as DELIVERED in db, the delivery is is specified by pId
 //$delivey送出后,manager点一个按钮,undelivered-》deliveried
 public void SendDelivery(Guid pId)
 {
     DataContextDataContext dc = new DataContextDataContext();
     dc.update_state_delivery((Guid?)pId, (int?)DeliveryState.DELIVERED);
 }
        public void ChangeState(DeliveryState pState)
        {
            state = pState;

            //~ synchronize to db, if need to maintain the state in db
            DataContextDataContext dc = new DataContextDataContext();
            dc.update_state_delivery(id, (int?)state);
        }