private void btnRmove_Click(object sender, EventArgs e)
        {
            var d = MessageBox.Show("Are you sure? ", "Delete Record", MessageBoxButtons.YesNo, MessageBoxIcon.Information);

            if (d == DialogResult.Yes)
            {
                if (listDisplay.GetSelected(listDisplay.SelectedIndex))
                {
                    var    tmp  = listDisplay.SelectedItem.ToString().Split(',');
                    string isbn = tmp[0].Replace("ISBN:", "");
                    DBConnection.deleteBook(isbn);
                    listDisplay.Items.Remove(listDisplay.SelectedItem);
                    MessageBox.Show("Book successfully deleted");
                }
            }
        }