protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
string oldPurchasePrice, OldsalePrice;
Decimal pprice = stock.GetPurchasePrice(Convert.ToInt32(ddlStock.SelectedValue.ToString()));
oldPurchasePrice = pprice.ToString();
OldPurchasePrice.Text = oldPurchasePrice;
Decimal sprice = stock.GetSalePrice(Convert.ToInt32(ddlStock.SelectedValue.ToString()));
OldsalePrice = sprice.ToString();
OldSalePrice.Text = OldsalePrice;
}