private void btnAddStudent_Click(object sender, EventArgs e)
        {
            //string rfid;
            //String fname;
            //decimal balance;

            //if (tbName.Text != "" && tbrfid.Text != "" && tbBalance.Text != "")
            //{
            //    rfid = Convert.ToString(tbrfid.Text);
            //    balance = Convert.ToDecimal(tbBalance.Text);
            //    fname = Convert.ToString(tbName.Text);
            //   int nrAdded=  RDH.AssignTheRFID(rfid, balance, fname);

            //    if (nrAdded > 0)
            //    {
            //        MessageBox.Show("Succesfully added to the database");
            //   }
            //    else
            //   {
            //       MessageBox.Show("Error while assigning rfid to the visitor");
            //   }
            //}
            string  rfid;
            String  fname;
            decimal balance;
            Visitor vistor = null;

            if (tbrfid.Text != "")
            {
                rfid = Convert.ToString(tbrfid.Text);
                //balance = Convert.ToDecimal(tbBalance.Text);
                //fname = Convert.ToString(tbName.Text);
                //int nrAdded = RDH.AssignTheRFID(rfid, balance, fname);
                RDH.UpdateRFIDStatus(vistor, rfid);

                //if (nrAdded > 0)
                //{
                MessageBox.Show("Succesfully added to the database");
                //}
                //else
                //{
                //   MessageBox.Show("Error while assigning rfid to the visitor");
                // }
            }
        }