Question

I have tried to program a inbox that display messages in the order they were received and then by if they have been read or not, it seemed to work for a while, but not it doesn’t. It may have only worked under certain circumstances maybe..

Anyway here is my query;

SELECT `id`, `from_userid`, `read`, max(sent) AS sent 
FROM (`who_messages`) 
WHERE `to_userid` = '41' 
GROUP BY `from_userid` 
ORDER BY `read` ASC, `sent` DESC

I believe the problem is that the messages are being grouped in the wrong order.. as the inbox is always showing as read, when new messages exist. I get the right time of the new messages, but I am guessing this because I selected max(sent).

Is my logic wrong? or can I sort and then group as all my efforts have resulted in ‘Every derived table must have its own alias’

Answer 1

“inbox that display messages in the order they were received and then by if they have been read or not … however it is suppose to be the latest message” – assumes read is a nullable date/time column, and messages are stored in the order they are sent (newer have larger id than older – autoid)

SELECT wm.id, wm.from_userid, (wm.read IS NULL) as unread, wm.sent
FROM (SELECT MAX(id) AS id FROM who_messages WHERE to_userid = '41' GROUP BY from_userid) sub
INNER JOIN who_messages wm ON sub.id = wm.id
ORDER BY wm.sent DESC, wm.read