Вот учу PL\SQL и вот чего придумал по запросу. Проверил - работает.
DECLARE
CURSOR icc_cur
IS
SELECT city, COUNT(*) FROM ID_CITY_CODE GROUP BY city;
v_city VARCHAR(20);
v_count NUMBER;
BEGIN
OPEN icc_cur;
LOOP
FETCH icc_cur INTO v_city, v_count;
EXIT
WHEN icc_cur%NOTFOUND;
INSERT INTO CITY_COUNT VALUES
(v_city, v_count
);
END LOOP;
CLOSE icc_cur;
SELECT * FROM CITY_COUNT;
END;