[Admin]

As done on this forum:

// get online users
$datecut=time()-$cookietimeout;
$headerguests=$DB_site->query_first("SELECT COUNT(*) AS count FROM session WHERE userid=0 AND lastactivity>$datecut");
$headerusers=$DB_site->query_first("SELECT COUNT(DISTINCT(userid)) AS count FROM session WHERE session.userid>0 AND session.lastactivity>$datecut");
$headeronline=$headerguests[count]+$headerusers[count];