function updateCard($addressBookId, $cardUri, $cardData)
{
$stmt = $this->pdo->prepare('UPDATE ' . $this->cardsTableName . ' SET carddata = ?, lastmodified = ?, size = ?, etag = ? WHERE uri = ? AND addressbookid =?');
$etag = md5($cardData);
$stmt->execute([$cardData, time(), strlen($cardData), $etag, $cardUri, $addressBookId]);
$this->addChange($addressBookId, $cardUri, 2);
return '"' . $etag . '"';
}