I'm currently desiging a forum application, I considered using a premade but decided against it as it's useful for me to learn some of the techniques. So I've written a fairly full featured forum... great.

One of the problems I want to solve is to include user data for each post, at the minute the post table includes the poster ID (obviously) and I added the poster's username at a later date so I didn't have to query the User DB for X number of posts in a thread. However, it's become apparent I now want to do this, usernames don't need to update retrospectively, however avatars, sigs, and especially post counts need to update actively, so data in some form needs keeping up to date somewhere...

What would be a good way of implementing this? I obviously don't want to include any more user data on the Posts DB table than necessary, but I'm struggling to find an easy way to do this short of querying the DB for each post in a thread, which is potentially going to create a lot of traffic.

How have other people solved this, I've been examining the code on some other open source apps but I can't find what I'm looking for.

Is it possible to select multiple records in one query? In which case I could build an array dynamically on each page request (eg 'SQL blah blah' then a for each loop to insert the ID's). Could I join the tables each time? Do I submit a query for each post? Hmm.