protected void btnDeleteOrder_Click(object sender, EventArgs e)
{
Button btnDetail = sender as Button;
GridViewRow grvr = btnDetail.NamingContainer as GridViewRow;
int orderid = int.Parse(GridView1.DataKeys[grvr.RowIndex].Value.ToString());
bus.DeleteOrder(orderid);
bus.DeleteOrderDetail(orderid);
ShowOrder();
}