[Freddie Bingham]

Try this

SELECT user.userid, user.username, count(userphotos.userid) AS total
FROM user
LEFT JOIN userphoto ON (userphoto.userid=user.userid)
GROUP BY user.userid
ORDER BY user.usergroupid DESC, user.username
LIMIT $offset, 15

This would give you then number of attachments each user has as I verified it. Since the above follows the same logic, it has to work.:

SELECT user.userid, user.username, count(attachment.userid) as attachmentcount
FROM user
LEFT JOIN attachment ON (user.userid=attachment.userid)
GROUP BY user.userid