public IEnumerable <CPhongKhamModel> getDSPhongKhamEnum(List <PhongKham> ds)
        {
            var query = (from pka in ds.AsEnumerable()
                         join pko in tc.getDSChuyenKhoa() on pka.ChuyenKhoaID equals pko.IDChuyenKhoa into val
                         from pko in val.DefaultIfEmpty()
                         select new CPhongKhamModel
            {
                MaPhongKham = pka.MaPhongKham,
                ChuyenKhoaID = pka.ChuyenKhoaID,
                ChuyenKhoa = pko == null ? "" : pko.TenChuyenKhoa,
                TenPhongKham = pka.TenPhongKham
            });

            return(query);
        }
 public List <ChuyenKhoa> getDSChuyenKhoa()
 {
     return(tc.getDSChuyenKhoa().ToList());
 }