MySQL Query join last comment to topic

I have a topic and topic_comments table. I want to join them both.

+------------+ +------------+
| Topic      | | Comments   |
+------------+ +------------+
| id         | | parent_id  |
| title      | | content    |
| createdate | | createdate |
| content    | | creator_id |
+------------+ +------------+

The join is on topic.id = topic_comments.parent_id. I want to show the topic with latest comment and order by latest comment createdate. And not show duplicate topics. Can anyone help me?

So far I have this:

select p.id, p.title, p.createdate, p.content, p.int_0 as reacties_total, p.char_1 as prio, p.char_0 as status, r.createdate as r_createdate, r.creator_id as r_creator_id, r.content as r_content
from pages p, topic_reacties r
where r.parent_id = p.id
  and p.parent_id = ' . $this->id . ' 
order by p.int_2 desc

This however doesn ‘t show topics without comments. It only returns topics with reactions.

Answer

SELECT title,content,max(createdate) as createdate 
FROM topic 
left join comments 
on topic.id=comments.parent_id 
group by title 
order by createdate desc;