if (lstItems.SelectedItems.Count > 0)
{
txtCode.Text = lstItems.SelectedItems[0].SubItems[1].Text;
txtName.Text = lstItems.SelectedItems[0].SubItems[2].Text;
txtPrice.Text = lstItems.SelectedItems[0].SubItems[3].Text.Substring(1);
txtStocks.Text = lstItems.SelectedItems[0].SubItems[4].Text;
id = int.Parse(lstItems.SelectedItems[0].Text);
btnAdd.Enabled = false;
btnUpdate.Enabled = true;
btnDelete.Enabled = true;
}