java.lang.IllegalArgumentException:   n   must   be   positive  

public List getMaxRsRandArticle(String hql, int num) {
    List list = new ArrayList();

    Transaction tx = null;
    Session session = HibernateUtil.getSession();
    try {
        tx = session.beginTransaction();
        Query query = session.createQuery(hql);
            log.info("随机HQL:"+hql);