private void btn_Del_Click(object sender, EventArgs e) { bll = new BLL_QuanLySP(); bool result = false; for (int i = dataGridView1.RowCount - 1; i > 0; i--) { if (dataGridView1.Rows[i].Cells["col_Check"].Selected) { int proid = Convert.ToInt32(dataGridView1.Rows[i].Cells["col_ProID"].Value); result = bll.DeletePro(ref err, proid); } } if (result) { MessageBox.Show("Xóa hoàn tất"); cbo_dm_SelectedIndexChanged(sender, e); } else { MessageBox.Show("Xóa thất bại"); } }