Is there a way to Search by Posts with No Staff replies on it

[Mittineague]

I was playing with some queries using group_users, topic_users and topics when I noticed a topics field moderator_posts_count and got excited!!!

I tried

SELECT topics.id as topic_id 
FROM topics 
WHERE topics.moderator_posts_count < 1 

not so lucky, there was a lot of difference from the results I got with the more complex query.