public interface ITrade

    {

        void UpdateTradeByTid(string Tid);

        bool CheckTrade(string Tid);

        void InsertTrade(TB_Trade trade);

        TB_Trade GetTrade(string Tid);

    }

    public class Trade : ITrade

    {

        public void UpdateTradeByTid(string Tid)

        {

            TB_Trade trade = GetTrade(Tid);

            if (trade == null)

            {

                trade = new TB_Trade();

                InsertTrade(trade);

            }

            else

            {

                using (GuoTBManageEntities context = new GuoTBManageEntities())

                {

                    context.Entry(trade).State = EntityState.Modified;

                    context.SaveChanges();

                }

            }

        }

        public bool CheckTrade(string Tid)

        {

            TB_Trade trade=GetTrade(Tid);

            return trade == null ? false : true;

        }

        public void InsertTrade(TB_Trade trade)

        {

            try

            {

                using (GuoTBManageEntities context = new GuoTBManageEntities())

                {

                    context.TB_Trades.Add(trade);

                    context.SaveChanges();

                }

            }