HAVING子句中的Oracle PL / SQL变量

我在将变量放入HAVING子句时遇到了一些麻烦，问题是我需要COUNT（*）大于该变量。

我正在使用ORACLE数据库XE 11.2

DECLARE


  cnt1 NUMBER;
  cnt2 NUMBER;
  res NUMBER;
BEGIN
  SELECT COUNT(*)
    INTO cnt1
    FROM BESTELLING;

  SELECT COUNT(*)
    INTO cnt2
    FROM ARTIKEL;

  res := cnt1 / cnt2;
END;
/

SELECT A.Naam, COUNT(*) AS HOEVEEL_VERKOCHT
FROM Artikel A, Winkelwagen W
WHERE A.Artikel_ID = W.Artikel_ID
AND W.Datum_Besteld IS NOT NULL
GROUP BY A.Naam
HAVING COUNT(*) > ?res?
ORDER BY COUNT(*) DESC;