private void dgvPhieuXuat_CellClick(object sender, DataGridViewCellEventArgs e)
        {
            try
            {
                isCheck           = 1;
                btnDelete.Enabled = true;
                txtMaPx.Text      = dgvPhieuXuat.CurrentRow.Cells[1].Value.ToString();
                txtMaNv.Text      = dgvPhieuXuat.CurrentRow.Cells[2].Value.ToString();
                cboMaSp.Text      = dgvPhieuXuat.CurrentRow.Cells[3].Value.ToString();
                cboMaKh.Text      = dgvPhieuXuat.CurrentRow.Cells[4].Value.ToString();
                cboSlx.Text       = dgvPhieuXuat.CurrentRow.Cells[5].Value.ToString();
                dtmNgayXuat.Text  = dgvPhieuXuat.CurrentRow.Cells[6].Value.ToString();
                txtPhanTram.Text  = dgvPhieuXuat.CurrentRow.Cells[7].Value.ToString();

                PhieuXuatHang.MaPxKh     = int.Parse(txtMaPx.Text);
                PhieuXuatHang.NgayXuatKh = DateTime.Parse(dtmNgayXuat.Text);
                double thanhTien = double.Parse(dgvPhieuXuat.CurrentRow.Cells[8].Value.ToString());
                txtThanhTien.Text = thanhTien.ToString("0,00.##");
                txtTongTien.Text  = thanhTien.ToString("0,00.##");

                px.MaSp = int.Parse(cboMaSp.Text);

                cboGiaSanPham.DataSource = pxbll.SelectGiaThanhSanPham(px);
                double giaSp = double.Parse(cboGiaSanPham.Text);
                cboGiaSanPham.Text = giaSp.ToString("0,00.##");
            }
            catch (Exception ex)
            {
                MessageBox.Show("Loi: " + ex.Message);
            }
        }