php mysql Group By to get latest record, not first record

Question

The Table:

(`post_id`, `forum_id`, `topic_id`, `post_time`) 
(79, 8, 4, \'2012-11-19 06:58:08\');
(80, 3, 3, \'2012-11-19 06:58:42\'),
(81, 9, 9, \'2012-11-1         


        

Answer 1

It's not very beautiful , but it works:

SELECT * FROM (SELECT  post_id, forum_id, topic_id FROM posts
ORDER BY post_time DESC) as temp
GROUP BY topic_id