Как изменить рейтинг?

    /**
     * Возвращает некешированный рейтинг пользователя
     * @param int $user_id ID пользователя
     * @return int
     */
    public static function getRating($user_id) {
 
        $inDB = cmsDatabase::getInstance();
 
		$rating = 0;
 
		$targets = $inDB->get_table('cms_rating_targets', 'is_user_affect = 1 ORDER BY user_weight', 'target, user_weight, target_table');
		if(!$targets) { return $rating; }
 
        $start_sql = "SELECT SUM( r.total_rating ) AS rating FROM cms_ratings_total r \n";
 
		foreach($targets as $target){
 
			$sql = "INNER JOIN {$target['target_table']} {$target['target']} ON
					 r.item_id = {$target['target']}.id AND
					 r.target = '{$target['target']}' AND
					 {$target['target']}.user_id = '{$user_id}' \n";
 
			$result  = $inDB->query($start_sql . $sql);
			$data    = $inDB->fetch_assoc($result);
			$rating += (int)@$data['rating'] * (int)$target['user_weight'];
 
		}
 
        return $rating;
 
    }