select distinct forums_messages.user_id, persons.first_names, persons.last_name, count(user_id) as num_msg, to_char(max(last_child_post), 'YYYY-MM-DD HH24:MI:SS') as last_post from persons, forums_messages where forums_messages.user_id = persons.person_id and forums_messages.forum_id = :forum_id group by forums_messages.user_id, persons.first_names, persons.last_name