edit button in grideview

protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
       {
           int id = Convert.ToInt16(GridView1.DataKeys[e.NewEditIndex].Values[0].ToString());

           cnn.Open();
           SqlCommand cmd = new SqlCommand("delete from call_details where id=" + id, cnn);
           int result = cmd.ExecuteNonQuery();
           cnn.Close();

           GridView1.DataBind();