void btn_Click(object sender, EventArgs e) { var selectedColumns = string.Empty; foreach (Control ctrl in Pub1.Controls) { if (ctrl.GetType().Name != "CheckBox" || ctrl.ID == "CB_CheckAll" || !(ctrl as CheckBox).Checked) { continue; } selectedColumns += ctrl.ID.Substring("CB_Col_".Length) + ","; } Response.Redirect(string.Format( "{0}?Step=3&FK_MapData={1}&FK_SFDBSrc={2}&STable={3}&SColumns={4}", Request.Url.AbsolutePath, this.FK_MapData, this.FK_SFDBSrc, this.STable ?? (Pub1.GetLBByID("LB_Table").SelectedItem.Value), selectedColumns)); }