SELECT DISTINCT ON (commclass_id, comminterpretation.commname)
/* there are 330 more comminterpretations than commclasses. some of these
multiple determinations have the same commname. */
*
FROM      commclass
LEFT JOIN comminterpretation USING (commclass_id)
ORDER BY commclass_id, comminterpretation.commname, comminterpretation_id
