private void frmAddDonNhapHang_Load(object sender, EventArgs e)
{
donNhapHang = new DonNhapHang();
dgvHangHoa.DataSource = hangBLL.LoadDanhSachHHCungCap();
cboLoaiHang.DataSource = loaiBLL.LoadAll();
cboLoaiHang.DisplayMember = "TenLoai";
cboLoaiHang.ValueMember = "ID";
cboLoaiHang.SelectedIndex = -1;
}