Oracle Multiset Union berbeda

DECLARE
   TYPE limbs_t IS TABLE OF limbs%ROWTYPE;

   l_limbs   limbs_t;
BEGIN
     SELECT l.nm, l.avg_len
       BULK COLLECT INTO l_limbs
       FROM limbs l
   ORDER BY l.nm;

   l_limbs := l_limbs MULTISET UNION l_limbs;
   DBMS_OUTPUT.put_line ('Lots of limbs! ' || l_limbs.COUNT);
END;
Old-fashioned Ostrich