Query returns additional rows

Question

I have this kind of table for simple chat:

messages table structure
+----+---------+-----------+---------+------+------+
| id | to_user | from_user | message         


        

Answer 1

Remove the group by clause in your in statement--it's useless in this case. It's returning a sent timestamp for each distinct pairing of to_user and from_user. You really just want the max sent where to_user or from_user equal some value. Lose the group by, and you'll return exactly one record showing the latest message either to or from a user.

It looks like this:

SELECT *
FROM `messages`
WHERE `sent`
IN (
   SELECT MAX( `sent` )
   FROM `messages`
   WHERE `from_user` = '1' --id of user who is requesting the list
   OR `to_user` = '1'  --id of user who is requesting the list
   )
LIMIT 0 , 30