$query = $this->db->update(
      //do something
    );

    if($query == 0)
    {
      $this->setMessage('error', 'There was an error: ' . $this->db->print_error());
    }
    else
    {
      wp_redirect(site_url('/user_data/'));
    }

public function redirect($url = false)
  {
    if(headers_sent())
    {
      $destination = ($url == false ? 'location.reload();' : 'window.location.href="' . $url . '";');
      echo die('<script>' . $destination . '</script>');
    }
    else
    {
      $destination = ($url == false ? $_SERVER['REQUEST_URI'] : $url);
      header('Location: ' . $destination);
      die();
    }
  }

add_action ('wp_loaded', 'clean_admin_referer');
function clean_admin_referer() {

if ( isset( $_REQUEST['condition1']) && isset($_REQUEST['condition2']) ) {

    if (current_user_can('administrator')) {

        <!-- do your database magic -->

        $_SERVER['REQUEST_URI'] = remove_query_arg( array( 'condition1', 'condition2' ));

        wp_redirect($_SERVER['REQUEST_URI']);

    }
}