protected void Button1_Click(object sender, EventArgs e) { DataTable d2 = d1.getdepart(DropDownList1.SelectedValue); { if (d2.Rows.Count > 0) { GridView1.DataSource = d1.getdepart(DropDownList1.SelectedValue); GridView1.DataBind(); } else { Response.Write("<script>alert('No data found on this airport! Select another')</script>"); } } }