QUERY: SELECT count(*) FROM onek;
count
-----
 1000
(1 row)

QUERY: SELECT count(*) AS random INTO RANDOM_TBL
  FROM onek WHERE oidrand(onek.oid, 10);
QUERY: INSERT INTO RANDOM_TBL (random)
  SELECT count(*)
  FROM onek WHERE oidrand(onek.oid, 10);
QUERY: SELECT random, count(random) FROM RANDOM_TBL
  GROUP BY random HAVING count(random) > 1;
random|count
------+-----
(0 rows)

QUERY: SELECT random FROM RANDOM_TBL
  WHERE random NOT BETWEEN 80 AND 120;
random
------
(0 rows)

