Question

I am creating a rails 3 application.

It has Groups (like social groups with memebers and so on and members can post on groups).
So my model is Group and Post, and group has_many posts (each of them (posts) obviously have group_id).

I am trying to figure out, how to get a list of groups sorted by the most recent post, including groups without any posts.

Thanks!

Answer 1

Depending on what columns you have, it could be something like

select g.group_id, g.group_name, max( p.post_date )
from   group g left join post p on g.group_id = p.group_id
group by g.group_id, g.group_name
order by max( p.post_date ) desc