public function getActiveVersion($mixID)
    {
        $queryBuilder = $this->connection->createQueryBuilder();
        $queryBuilder->select(['select']);
        $queryBuilder->from('tl_version');
        $queryBuilder->andWhere($queryBuilder->expr()->eq('tl_version.pid', ':pid'));
        $queryBuilder->setParameter(':pid', $mixID);
        $queryBuilder->andWhere($queryBuilder->expr()->eq('tl_version.fromTable', ':fromTable'));
        $queryBuilder->setParameter(':fromTable', $this->source);
        $queryBuilder->andWhere($queryBuilder->expr()->eq('tl_version.active', ':active'));
        $queryBuilder->setParameter(':active', 1);

        $statement = $queryBuilder->execute();
        if (0 === $statement->rowCount()) {
            return null;
        }

        return $statement->fetch(\PDO::FETCH_OBJ)->version;
    }