private void confirm_pay()
        {
            SqlConnection con = new SqlConnection(dbclass.constring);
            con.Open();
            string query = "UPDATE  tbl_customer  SET Status=@Status WHERE Vuncher=@Vuncher";
            SqlCommand cmd = new SqlCommand(query, con);
            cmd.Parameters.AddWithValue("@Status", txt_pay.Text);
            cmd.Parameters.AddWithValue("@Vuncher", txt_vuncher2.Text);
            cmd.ExecuteNonQuery();
            MessageBox.Show("Payment Confirmed");
            con.Close();
            load_data();


            //string query2 = "SELECT MAX(No) from tbl_product_sale_final where Barcode=@Barcode";
            //SqlCommand cmd2 = new SqlCommand(query2, con);
            //cmd2.Parameters.AddWithValue("@Barcode", txt_barcode.Text);
            //con.Open();
            //cmd2.ExecuteNonQuery();
            //txt_No.Text = cmd2.ExecuteScalar().ToString();
            //con.Close();
        }