What is wrong?

Question

private void button4_Click(object sender, EventArgs e)
        {
            if (bar_code1DataGridView.SelectedRows.Count > 0)
            {

                DataGridViewRow dr = bar_code1DataGridView.SelectedRows[0];
                if (!string.IsNullOrEmpty(dr.Cells["dataGridViewTextBoxColumn1"].Value.ToString()))
                {

                    String cs = "Data Source=.\\SQLEXPRESS;Initial Catalog=barcode;Integrated Security=True";
                    using (SqlConnection openCon = new SqlConnection(cs))
                    {


                        using (SqlCommand querySaveStaff = new SqlCommand("DELETE FROM bar_code1 WHERE id=@id", openCon))
                        {

                            // querySaveStaff.Parameters.Add("@id",SqlDbType.Int).Value=idTextBox.Text;
                            querySaveStaff.Parameters.AddWithValue("@id", 0);

                            openCon.Open();
                            querySaveStaff.ExecuteNonQuery();
                            openCon.Close();

                        }

                    }

                    using (SqlConnection openCon = new SqlConnection(cs))

                    {

                        string saveStaff = "SELECT * FROM dbo.bar_code1 ";
                        openCon.Open();
                        using (SqlDataAdapter querySaveStaff = new SqlDataAdapter(saveStaff, cs))
                        {
                            querySaveStaff.Fill(barcodeDataSet.bar_code1);
                            bar_code1DataGridView.DataSource = barcodeDataSet.bar_code1;
                            bar_code1DataGridView.Update();
                            bar_code1DataGridView.Refresh();
                        }

                    }
                }
            }
        }