hoten, diachi, dienthoai, ngaymua, null);
billDAO.addBill(hd);
Set<Billdetail> billdetails = new HashSet<Billdetail>();
for (int i = 0; i < sanphams.size(); i++) {
Billdetail dt = new Billdetail(hd, sanphams.get(i),
sanphams.get(i).getPrice(), soluongs.get(i));
billDAO.addBill(dt);
}