Ok, I was told that the query I posted earlier for the last poster fix, might give false information at a point in the future. Here is the updated one. This one works, I've tested it.
PHP Code:
$dposteurs=$DB_site->query_first("SELECT post.dateline, thread.threadid, user.username
FROM post, thread
LEFT JOIN user ON user.userid = post.userid
WHERE thread.forumid = $forumid AND thread.threadid = post.threadid
ORDER BY post.dateline DESC
LIMIT 1");
Just use $dposteurs[username] for the username. I'm not sure what tio use to pull the userid out of this query, though. Can someone lend a hand?