public void GetAllToGridView()
{
List <EL.HangHoa> listHangHoa = hangHoaBUS.ViewAll();
dataTable.Rows.Clear();
foreach (EL.HangHoa hanghoa in listHangHoa)
{
dataTable.Rows.Add(hanghoa.MaHang, hanghoa.TenHang, hanghoa.NoiChua, hanghoa.SoLuongHang, hanghoa.GiaHang);
}
dataGridView1.DataSource = dataTable;
}