Page 220 syntax:
SELECT f.name,
COALESCE(MAX(m.date_entered), 'N/A') AS last_post
FROM forums AS f -- my tablename is 'forums'.
LEFT JOIN messages AS m
USING (forum_id)
GROUP BY (m.forum_id)
ORDER BY m.date_entered DESC;
Results in this error:
#1055 - Expression #1 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'rich_forum.f.name' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by