private void LoadData()
{
dgvHang.DataSource = bll.GetHangHoa(txtMaHH.Text, txtTenHH.Text);
dgvHang.AutoResizeColumns();
dgvHangMua.DataSource = bll.GetTableHangMua(hangmua);
dgvHangMua.AutoResizeColumns();
if (string.IsNullOrEmpty(txtMaKH.Text.Trim()))
{
txtTong.Text = bll.TinhTongTien(hangmua).ToString();
}
else
{
txtTong.Text = bll.TinhTongTien(Convert.ToInt32(txtMaKH.Text), hangmua).ToString();
}
}