public DataTable getAllCoursebySid(int sid)
        {
            CourseService couService = new CourseService();
            DataTable dt = couService.getCourseBySid(sid,1);
            dt.Columns.Add("trans_week", typeof(string));
            foreach (DataRow dr in dt.Rows)
            {
                if (dr["week"].ToString() == "1")
                {
                    dr["trans_week"] = "1-16";
                }
                else if (dr["week"].ToString() == "2")
                {
                    dr["trans_week"] = "1-8";
                }
                else
                {
                    dr["trans_week"] = "9-16";
                }

            }
            TeacherService teachService = new TeacherService();
            dt.Columns.Add("tname", typeof(string));
            foreach (DataRow dr in dt.Rows)
            {
                dr["tname"] = teachService.getTnameByTid(int.Parse(dr["tid"].ToString()));
            }
            return dt;
        }