public void DLTrenTungTrang_KhachHang()
        {
            dgvKhachHang.DataSource = bus_khachhang.PhanTrang_KhachHang(currentPageKhachHang);
            BuocDlVaoCacDieuKhien_KhachHang();

            txtTrangKH.Text     = currentPageKhachHang.ToString();
            lblTongTrangKH.Text = "/" + bus_khachhang.totalPage;
        }