public function connect(): DatabaseConnection
    {
        if (null !== $this->pdo) {
            return $this;
        }

        try {
            $pdoCreator = $this->getPdoCreator();
            $this->pdo  = $pdoCreator($this->configuration);
            $this->pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
            $this->pdo->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
            if ($this->configuration->hasInitialQuery()) {
                $this->pdo->query($this->configuration->getInitialQuery());
            }
        } catch (PDOException $pdoe) {
            throw new DatabaseException($pdoe->getMessage(), $pdoe);
        }

        return $this;
    }