Question

Let say i have three table (post, wall, photo)

post (id, post_uid, post_content, post_timestamp)

wall (id, wall_from, wall_to, wall_content, wall_timestamp)

photo (id, photo_gid (reference from gallery id), photo_caption, photo_filename, photo_timestamp)

all i want to do is join these three table but the order is from post_timestamp, wall_timestamp, and photo_timestamp into single query or single result.

what should i do? should i create new table, or is it possible to order from three field?

Answer 1

To order by latest first

select *
from post
join wall on ...
join photo on ...
where ...
order by greatest(post_timestamp, wall_timestamp, photo_timestamp) desc

or, to order by earliest first:

...
order by least(post_timestamp, wall_timestamp, photo_timestamp)