private void btnLapPhieuMoi_Click(object sender, EventArgs e)
        {
            i = 0;
            btnLapPhieuMoi.Enabled = false;
            btnThemSP.Enabled      = true;
            btnIn.Enabled          = true;
            cboMaDH.Enabled        = false;
            txtMaPGNCC.ReadOnly    = true;
            txtSoPG.Text           = PhieuGiaoHangBUS.GetIDPhieuGiao();
            txtMaSP.ResetText();
            txtTenSP.ResetText();
            txtSoLuong.ResetText();
            dtkNgayGiao.Value = DateTime.Now;
            dgvDanhSach.Rows.Clear();
            // Thêm vào auto complete.
            AutoCompleteStringCollection auto = new AutoCompleteStringCollection();

            foreach (DataRow row in SanPhamBUS.DanhSachSPTheoDDH(cboMaDH.SelectedValue.ToString()).Rows)
            {
                auto.Add(row["MaSanPham"].ToString());
            }
            txtMaSP.AutoCompleteMode         = AutoCompleteMode.Suggest;
            txtMaSP.AutoCompleteSource       = AutoCompleteSource.CustomSource;
            txtMaSP.AutoCompleteCustomSource = auto;
        }