internal void SendMessage(int roomNum, int time, DateTime now)
        {
            string[]       sql = { "select t1.no,t2.name,t1.seat_no,t1.time_end,t2.wechat from tb_seat_student as t1,tb_student as t2 where t1.room=@room and t1.time_end<@nw and t1.isoutdate=0 and t1.issend_" + time + "_message=0 and t1.no=t2.no",
                                   "update tb_seat_student set issend_" + time + "_message=1 where room=@room and time_end<@nw and isoutdate=0 and issend_" + time + "_message=0" };
            SqlParameter[] sp1 =
            {
                new SqlParameter("@room", roomNum),
                new SqlParameter("@nw",   now.AddMinutes(time))
            };
            DataTable dt           = SqlServerHelper.ExecuteDataTable(sql[0], sp1);
            string    access_token = GetAccessToken();

            //发送消息
            foreach (DataRow item in dt.Rows)
            {
                Send(access_token, item[0].ToString(), roomNum.ToString(), seat_no2tableseat(MyConvert.toInt(item[2])), time.ToString(), MyConvert.toString(item[3]));
            }
            //发送消息结束。
            SqlParameter[] sp2 =
            {
                new SqlParameter("@room", roomNum),
                new SqlParameter("@nw",   now.AddMinutes(time))
            };
            SqlServerHelper.ExecuteNonQuery(sql[1], sp2);
        }
        /// <summary>
        /// 系统启动时扫描一次本自习室座位的使用情况。
        /// </summary>
        /// <param name="room"></param>
        /// <param name="SetColor"></param>
        public void Scan(int room, RemoteSetColor SetColor)
        {
            string    sql = "select no from tb_seat where anyone=1";
            DataTable dt  = SqlServerHelper.ExecuteDataTable(sql);

            foreach (DataRow item in dt.Rows)
            {
                SetColor((int)item[0], Brushes.Red);
            }
        }