+ # For every class, posinclass is dense from 1 to maxposinclass,
+ # apart from the commods for which it is zero.
+ SELECT commodclass,commodclassid,posinclass,count(*)
+ FROM commods NATURAL JOIN commodclasses
+ WHERE posinclass > 0
+ GROUP BY commodclassid,posinclass
+ HAVING count(*) > 1;
+ SELECT commodclass,commodclassid,count(*)
+ FROM commods NATURAL JOIN commodclasses
+ WHERE posinclass > 0
+ GROUP BY commodclassid
+ HAVING count(*) != maxposinclass;
+ SELECT *
+ FROM commods NATURAL JOIN commodclasses
+ WHERE posinclass < 0 OR posinclass > maxposinclass;
+