private void cboLoaiSp_TextChanged(object sender, EventArgs e)
        {
            if (cboLoaiSp.Text == "")
            {
                HienThiThongKe();
                return;
            }

            cboNhaSx.Text = "";

            int i = 0;

            tk.TenLoai = cboLoaiSp.Text;
            List <ThongKe> tklist = tkbll.ThongKeDonDatHangTheoLoaiSp(tk);

            dgvThongKeDoDh.Rows.Clear();
            foreach (ThongKe tks in tklist)
            {
                DataGridViewRow row = new DataGridViewRow();
                row.CreateCells(dgvThongKeDoDh);
                row.Cells[0].Value = i + 1;
                row.Cells[1].Value = tks.MaSp;
                row.Cells[2].Value = tks.TenSp;
                row.Cells[3].Value = tks.TenLoai;
                row.Cells[4].Value = tks.TenSx;
                row.Cells[5].Value = tks.Sld;

                dgvThongKeDoDh.Rows.Add(row);
                ++i;
                Sum += i;
            }
            cboTongDodh.Text = i.ToString();
        }
        private void cboLoaiSp_TextChanged(object sender, EventArgs e)
        {
            try
            {
                if (cboLoaiSp.Text == "")
                {
                    HienThiThongKe();
                    return;
                }

                cboNhaSx.Text = "";

                int i = 0;

                tk.TenLoai = cboLoaiSp.Text;
                List <ThongKe> tklist = tkbll.ThongKeDonDatHangTheoLoaiSp(tk);

                dgvThongKeDonHang.Rows.Clear();
                foreach (ThongKe tks in tklist)
                {
                    DataGridViewRow row = new DataGridViewRow();
                    row.CreateCells(dgvThongKeDonHang);
                    row.Cells[0].Value = i + 1;
                    row.Cells[1].Value = tks.MaSp;
                    row.Cells[2].Value = tks.TenSp;
                    row.Cells[3].Value = tks.TenLoai;
                    row.Cells[4].Value = tks.TenSx;
                    row.Cells[5].Value = tks.Sld;

                    dgvThongKeDonHang.Rows.Add(row);
                    ++i;
                }
                cboTongDondh.Text      = i.ToString();
                cboTongSldh.DataSource = tkbll.TongSldhTheoLoaiSp(tk);
            }
            catch (Exception ex)
            {
                MessageBox.Show("Lỗi Loại Sản Phẩm!" + ex.Message);
            }
        }