Bare with me as I try to explain.
I have two tables: Topics and Comments. topic.id is indexed to comment.topicid, for every comment that is indexed to topic.id I want to +1 a column in my comments table, called comments.replies.
I can do this incredibly easy with PHP, however, I'm left wondering if it's at all possible with just MySQL?
Here's my relationship diagram for better understanding:
http://i.imgur.com/1nICb.png