SQL getting max id field on a LEFT JOIN
Try
SELECT messages.*, T2.photoFROM messagesLEFT JOIN (SELECT userid, MAX(id) AS maxid FROM tblimages GROUP BY userid) AS T1ON messages.user_id = T1.useridLEFT JOIN tblimages AS T2ON T2.id = T1.maxidORDER BY messages.msg_id DESCwhich finds max(id) for each user in tblimages, then uses that to join each user to the latest photo for that user.