public Result <List <Diem_ett> > select_by_fields(string input, string how)
        {
            Result <List <Diem_ett> > rs = new Result <List <Diem_ett> >();

            try
            {
                List <Diem_ett>       lst = new List <Diem_ett>();
                IQueryable <tbl_diem> dt  = null;
                switch (how)
                {
                case "masv":
                    dt = db.tbl_diems.Where(o => o.masv.Contains(input));
                    break;

                case "tensv":
                    break;

                case "mamon":
                    dt = db.tbl_diems.Where(o => o.mamon.Contains(input));
                    break;

                case "tenmon":
                    break;

                case "diem":
                    dt = db.tbl_diems.Where(o => o.diem.Contains(input));
                    break;

                default:
                    break;
                }

                if (dt.Count() > 0)
                {
                    foreach (tbl_diem item in dt)
                    {
                        Diem_ett temp = new Diem_ett(item);
                        lst.Add(temp);
                    }

                    rs.data      = lst;
                    rs.errorCode = ErrorCode.Sucess;
                }
                else
                {
                    rs.data       = null;
                    rs.errorCode  = ErrorCode.NaN;
                    rs.errorInfor = Constants.empty_data;
                }
                return(rs);
            }
            catch (Exception e)
            {
                rs.data       = null;
                rs.errorCode  = ErrorCode.False;
                rs.errorInfor = e.ToString();
                return(rs);
            }
        }
        public Result <List <Diem_ett> > select_all_diem()
        {
            Result <List <Diem_ett> > rs = new Result <List <Diem_ett> >();

            try
            {
                List <Diem_ett> lst = new List <Diem_ett>();
                var             dt  = db.tbl_diems;
                if (dt.Count() > 0)
                {
                    foreach (tbl_diem item in dt)
                    {
                        Diem_ett temp = new Diem_ett(item);
                        lst.Add(temp);
                    }

                    rs.data      = lst;
                    rs.errorCode = ErrorCode.Sucess;
                }
                else
                {
                    rs.data       = null;
                    rs.errorCode  = ErrorCode.NaN;
                    rs.errorInfor = Constants.empty_data;
                }


                return(rs);
            }
            catch (Exception e)
            {
                rs.data       = null;
                rs.errorCode  = ErrorCode.False;
                rs.errorInfor = e.ToString();
                return(rs);
            }
        }