Hey Christian,
thank you very much!
After writing the last post, i found this post: http://lists.typo3.org/pipermail/typo3-german/2010-June/069342.html
Just a hint for our english users in the community:
You can look into following code for deleting the user session:
$user = get_object_vars($GLOBALS["TSFE"]->fe_user);
$uid = $user['user']['uid'];
$ses_id = $GLOBALS["TSFE"]->fe_user->id;
if (!empty($uid)) {
$res = $GLOBALS['TYPO3_DB']->exec_SELECTquery('ses_id', 'fe_sessions', 'ses_userid= ' . $uid);
while ($row = $GLOBALS['TYPO3_DB']->sql_fetch_assoc($res)) {
$rows[] = $row;
}
if (sizeof($rows) > 1) {
$query = tx_pp_fc_db::buildQueryArray('ses_id',,);
$res = $GLOBALS['TYPO3_DB']->exec_DELETEquery('fe_sessions', 'ses_userid =' . $uid . ' AND ses_id != '".$ses_id."'');
}
}