SELECT DISTINCT problems

[Mistah Roth]

My script displays the last 5 threads, a user has posted in. The main query is as follows:

SELECT distinct threadid FROM ". TABLE_PREFIX . "post WHERE userid = " . $vbulletin->userinfo['userid'] . " ORDER BY postid DESC LIMIT 5

That should work... because if you remove DISTINCT it shows the last posts you made including duplicates of the same thread if you posted more than once in a thread.

For some reason, when you add DISTINCT, it does not return the last 5 threads posted in. For some reason it skips any older threadids. If I remove the distinct from the query, it shows the last 5 posts properly. The problem is we can't have repeats, so DISTINCT is supposed to solve that.

Anyone have any idea whats going wrong? If all else fails I'll just make it so that it filters out doubles with PHP code.... not as efficient as I'd like it though, there should be no reason the query doesnt work.