private void RefreshTime() //刷新时间的方法
    {
        //TimeSpan ts = this.dtExam - DateTime.Now; //时间差
        TimeSpan ts = DateTime.Parse(Session["LimitTime"].ToString()) - DateTime.Now;

        this.lbDays.Text   = ts.Days.ToString().PadLeft(2, '0');
        this.lbHour.Text   = ts.Hours.ToString().PadLeft(2, '0');
        this.lbMinute.Text = ts.Minutes.ToString().PadLeft(2, '0');
        this.lbSecond.Text = ts.Seconds.ToString().PadLeft(2, '0');
        try
        {
            helper.ExcuteCommandInt("update  Items set LimitTime='"
                                    + DateTime.Now.AddDays(int.Parse(lbHour.Text)).AddHours(int.Parse(lbHour.Text)).AddMinutes(int.Parse(lbMinute.Text)).AddSeconds(int.Parse(lbSecond.Text)) + "',Days="
                                    + int.Parse(lbHour.Text) + ",Hours="
                                    + int.Parse(lbHour.Text) + ",Minutes="
                                    + int.Parse(lbMinute.Text) + ",Seconds="
                                    + int.Parse(lbSecond.Text) + " Where IID="
                                    + int.Parse(Session["SeckillID"].ToString()) + "");
        }
        catch (Exception ex)
        {
            Response.Write(ex.Message); timerCD.Enabled = false;
        }
    }