I found a good php code if your website in php you can use this code. I know this post is about 3 years old but to help others I am pasting this code.

PHP Code:
<?
Session_start();
$today = time();
$query="INSERT into logged_in (Today, SessionID, CurrentPage, BrowserType, IP) VALUES ('".$today."','".$_SESSION['sesid']."','".$_SERVER['PHP_SELF']."','".$_SERVER['HTTP_USER_AGENT']."','".$_SERVER['REMOTE_ADDR']."')";
$result = mysql_query($query);
?>

Regards,
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