private void LoadData()
{
txtMaHang.Enabled = false;
gdv_HH.DataSource = bs_hh.getListHangHoa();
cboLoai.DataSource = hh.getTheLoai();
cboLoai.DisplayMember = "TenLoai";
cboLoai.ValueMember = "MaLoai";
cboTH.DataSource = hh.getThuongHieu();
cboTH.DisplayMember = "TenTH";
cboTH.ValueMember = "MaThuongHieu";
}