protected void deliverSearchB_OnClick(object sender, EventArgs e) { BlUser user = (BlUser)Session["user"]; //get input values string searchBys = DeliverSearchBy.Items[DeliverSearchBy.SelectedIndex].Value; string value = DeliverSearchVal.Text; //get data DataTable customers = user.DeliversSearch($"(Users.{searchBys}='{value}')"); bool isExist = BindTable(customers, DeliveriesTable); DeliverMSG.Text = !isExist ? "Not valid search value" : "";//error massage }