public function createCard($addressBookId, $cardUri, $cardData)
    {
        $stmt = $this->pdo->prepare('INSERT INTO '.$this->cardsTableName.' (carddata, uri, lastmodified, addressbookid, size, etag) VALUES (?, ?, ?, ?, ?, ?)');

        $etag = md5($cardData);

        $stmt->execute([
            $cardData,
            $cardUri,
            time(),
            $addressBookId,
            strlen($cardData),
            $etag,
        ]);

        $this->addChange($addressBookId, $cardUri, 1);

        return '"'.$etag.'"';
    }