public function delete()
 {
     $sql = "SELECT priority " . "FROM " . $this->table_name() . " " . "WHERE id = " . $this->get_id();
     global $wpdb;
     $current_priority = $wpdb->get_var($sql);
     $sql = "UPDATE " . $this->table_name() . " " . "SET priority = priority - 1 " . "WHERE priority > {$current_priority}";
     $wpdb->query($sql);
     parent::delete();
 }