Question

So, i have this table structure

+----+---------+-----------+---------+------+---------------------+
| id | to_user | from_user | message | read | sent                |
+----+---------+-----------+---------+------+---------------------+
|  1 |      2  |        1  | test    |    0 | 2012-01-11 13:20:14 |
+----+---------+-----------+---------+------+---------------------+

And as you can see i use this for very simple chat, and now what i wanna do is get the list of each conversations. So i need to find a way of selecting one last message from conversation which each user. so i need something like

   select * 
   from `messages` 
   where `to_user` = 2 --(this is my user id)
          and `to_user` = `from_user` 
   LIMIT 1

Now i know that LIMIT would always return 1 record and other logic is probably not so good, anyways if anyone get’s what i want here, could help me a little 🙂

Answer 1

An IN() subquery selects the id of each row having the most recent sent between two users. The outer query selects the remaining columns for each id returned from the subquery.

Update fixed the HAVING clause…

SELECT * FROM table WHERE id IN (
  SELECT id FROM table GROUP BY to_user, from_user HAVING sent = MAX(sent)
);