$books = q("SELECT id, ctag FROM %s%saddressbooks WHERE `namespace` = %d AND `namespace_id` = %d AND `uri` = '%s'",
CALDAV_SQL_DB, CALDAV_SQL_PREFIX, CARDDAV_NAMESPACE_PRIVATE, IntVal($uid), dbesc(CARDDAV_FRIENDICA_CONTACT));
$ctag = $books[0]["ctag"];
$books = q("SELECT id, ctag FROM %s%saddressbooks WHERE `namespace` = %d AND `namespace_id` = %d AND `uri` = '%s'",
CALDAV_SQL_DB, CALDAV_SQL_PREFIX, CARDDAV_NAMESPACE_PRIVATE, IntVal($uid), dbesc(CARDDAV_FRIENDICA_CONTACT));
$ctag = $books[0]["ctag"];