public function sqlQuery($queryString)
    {
        try {
            // execute query
            $query = $this->connection->prepare(
                $queryString,
                [\PDO::ATTR_CURSOR => \PDO::CURSOR_FWDONLY]
            );
            $query->execute();

            return $query;
        } catch (\PDOException $e) {
            throw new \Exception($e->getMessage());
        }
    }