private void btnBaoCao_Click(object sender, EventArgs e) { dgvDanhSach.DataSource = SachBUS.BaoCaoNhapKho(dtkNgay.Value); Custom(); dgvDanhSach.ClearSelection(); int TongCong = 0; for (int i = 0; i < dgvDanhSach.RowCount; i++) { TongCong = TongCong + int.Parse(dgvDanhSach.Rows[i].Cells[2].Value.ToString()); } txtTongcong.Text = TongCong.ToString(); }