private void cboNhaSx_TextChanged(object sender, EventArgs e)
        {
            if (cboNhaSx.Text == "")
            {
                DanhSachThongKe();
                return;
            }

            //cboTenSp.Text = "";

            int i   = 0;
            int Sum = 0;

            tk.TenSx = cboNhaSx.Text;
            List <ThongKe> tklist = tkbll.ThongKePHieuXuatTHeoNhaSx(tk);

            dgvThongKePhieuXuat.Rows.Clear();
            foreach (ThongKe tks in tklist)
            {
                DataGridViewRow row = new DataGridViewRow();
                row.CreateCells(dgvThongKePhieuXuat);
                row.Cells[0].Value = i + 1;
                row.Cells[1].Value = tks.MaSp.ToString();
                row.Cells[2].Value = tks.TenSp.ToString();
                row.Cells[3].Value = tks.TenLoai.ToString();
                row.Cells[4].Value = tks.TenSx.ToString();
                row.Cells[5].Value = tks.TenKh.ToString();
                row.Cells[6].Value = tks.Slx.ToString();
                row.Cells[7].Value = tks.TongTien;
                row.Cells[8].Value = tks.PhanTram.ToString();
                row.Cells[9].Value = tks.ThanhTien;

                dgvThongKePhieuXuat.Rows.Add(row);
                ++i;
                Sum += i;
            }
            cboTongPhieuXuat.Text = i.ToString();

            List <ThongKe> tklist1 = tkbll.TinhTongSlpxTheoNhaSanXuat(tk);
            List <ThongKe> tklist2 = tkbll.TinhTongThanhTienTheoNhaSanXuat(tk);

            foreach (ThongKe tks1 in tklist1)
            {
                cboTongSoLuongXuat.Text = tks1.Slx.ToString();
            }
            foreach (ThongKe tks2 in tklist2)
            {
                cboTongTien.Text = tks2.ThanhTien.ToString();
            }
        }