How to select the title with the latest datetime?

Question

I have these two tables in mysql:

posts (id)
post_titles (id, post_id, title, datetime, user_id)
post_contents (id, post_id, content, datetime, user_id)
post_statuses (id, post_id, status, datetime, user_id)

posts (id) == posts_titles (post_id)

In the post_titles and post_contents can be multiple entries for 1 posts (id) .

What i need, is to select the title which has the latest datetime. I would have to select it all by using the posts (id) . How could i do that?

EDIT: i need to select the latest title and latest content together or latest title, latest content and latest status.

Answer 1

Order by the column you are interested in (datetime in this case) and do a limit of 1. This will order the rows by datetime in descending order (newest will be first). And then limit 1 to just get the first row.

SELECT * FROM post_titles ORDER BY datetime DESC LIMIT 1;

Answer 2

Try this:

SELECT t.title, c.content
FROM post_titles t 
JOIN post_contents c ON t.post_id = c.post_id
WHERE 
t.datetime = 
    (SELECT MAX(x.datetime) FROM post_titles x WHERE t.post_id = x.post_id)
AND 
c.datetime = 
    (SELECT MAX(y.datetime) FROM post_contents y WHERE c.post_id = y.post_id);

I'm assuming that all the datetime are equal, because when you add something on the tables, the content are created at the same time.

EDIT: Now it doesn't matter if the datetime are equal. Check if it works.

Answer 3

To build on the answer from Mark S (I can't figure out how to quote or link to his answer...)

Since there are datetime fields on both post_title and post_contents tables, you'll have to specify which table's column to reference as you do the ordering, like this:

SELECT `title`, `content`
FROM `post_titles` t
    JOIN `post_contents` c USING (`post_id`)
ORDER BY t.datetime DESC
LIMIT 1