help with SQL select and php

[nezbo]

Hi all

 

I am tring to sort the content of my forum by the post comments...

 

i.e. i am trying to sort the form by most recent comment...

 

this is my SQL i have so far

 

$result = @mysql_query("SELECT forumID, forumHedder, forumBoddy, dateStamp, userID, email, valid , IF((SELECT TOP 1 timeStamp FROM forum_replies WHERE forum.forumID = forumID ORDER BY timeStamp DESE) = 0, forum.dateStamp, timeStamp) FROM forum WHERE valid=0 ORDER BY dateStamp DESC LIMIT " . $pages . " , 30");

 

I want to order be the  timeStamp FROM forum_replies but not all posts have been responded to so it will need to be check against the main post date forum.dateStamp...

 

Hope this make sence?