private void cboDVD_SelectedIndexChanged(object sender, EventArgs e)
        {
            //if resetting combo, ignore
            if (cboDVD.SelectedIndex == -1)
            {
                return;
            }

            //find DVD Details
            DVD updDVD = new DVD();

            updDVD.getDVD(Convert.ToInt32(cboDVD.Text.Substring(0, 3)));

            if (updDVD.getDVDId().Equals(0))
            {
                MessageBox.Show("No details found", "Error!", MessageBoxButtons.OK, MessageBoxIcon.Error);
                txtDVDId.Focus();
                return;
            }

            //display DVD details

            txtDVDId.Text          = updDVD.getDVDId().ToString("000");
            txtDVDTitle.Text       = updDVD.getTitle();
            txtDVDDescription.Text = updDVD.getDescription();
            txtDVDYearRelease.Text = updDVD.getYear().ToString();
            txtRateCode.Text       = updDVD.getRateCode();

            //display details
            grpDVD.Visible = true;
        }