private void SearchForInvoice_Click(object sender, EventArgs e)
{
Bills bl = bc.search("invoice", Int32.Parse(Search.Text));
if (bl != null)
{
Bill_Id.Text = bl.bill_id.ToString();
Products.SelectedValue = bl.product_id;
Unit_Price.Text = bl.unit_price.ToString();
Quantity.Text = bl.quantity.ToString();
Provider.Text = bl.client;
Date.Text = bl.date;
}
}