Hibernate 更新某个值

Question

我编写了一个方法，如果它具有特定标识符，则选择或更新一个值：

@Transactional
public List<Settings> getSettingsByParameter(String identifier) throws Exception {
    log.info("get resultsList by " + identifier);

    if(identifier.isEmpty()) {
        throw new Exception("Identifier is empty!");
    }

    if(identifier == "today") {
        //update today field
        String query = "UPDATE settings SET value=TODAY() where identifier = '" + identifier + "'";
        em.merge(em.createQuery(query, Settings.class).getSingleResult()); 
    }

    String query = "SELECT p FROM Settings p WHERE identifier = '" + identifier + "'";
    List<Settings> resultList = em.createQuery(query, Settings.class).getResultList(); 

    return resultList;
}

但是，我遇到了一个异常：

java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: settings is not mapped [UPDATE settings SET value=TODAY() where identifier = 'today']

为什么以及如何使用 hibernate 和 hsqldb？

非常感谢您的回答！

Answer 1

Hibernate 对类名区分大小写。尝试在 Settings 类中使用大写的 S：

String query = "UPDATE Settings SET value=TODAY() where identifier = '" + identifier + "'";