private void BaoCaoTieuDe_Load(object sender, EventArgs e)
        {
            tdbul = new TieuDeBUL();
            tlbul = new TheLoaiBUL();
            pdt   = new PhieuDatTruocBUL();
            ptt   = new PhieuThueTraBUL();
            dvd   = new DVDBUL();

            treeView1.Nodes.Clear();
            foreach (eTheLoai td in tlbul.getTheLoais())
            {
                TreeNode n = new TreeNode(td.tenTheLoai);
                n.Tag = td.id_TheLoai;
                treeView1.Nodes.Add(n);
            }
        }
        private void BaoCaoKhachHang_Load(object sender, EventArgs e)
        {
            khbul = new KhachHangBUL();
            phieu = new PhieuThueTraBUL();
            td    = new TieuDeBUL();
            tl    = new TheLoaiBUL();
            dvd   = new DVDBUL();

            List <eKhachHang> ls = khbul.getKhachHangs();

            dgv_dskh.DataSource = ls;
            FormatLaiDataGridviewkh(dgv_dskh);

            txt_totalkhnop.Text  = tongkhno().ToString();
            txt_totaldiatra.Text = tongkhthue().ToString();

            cb_listkh.Items.Add("Tất Cả");
            cb_listkh.Items.Add("Khách hàng quá hạn trả đĩa");
            cb_listkh.Items.Add("Khách hàng nợ phí trễ hạn");
            cb_listkh.SelectedIndex = 0;
        }