$rm = db->query_first_slave("SELECT vb_user.userid, vb_user.username, vb_userrank.title, vb_userrank.url_image 
FROM vb_user 
JOIN vb_userrank 
ON vb_user.pogon = vb_userrank.id ");

while($row = mysql_fetch_assoc($rm)) {
    echo $row['username'];
}