如何使用HQL以小时为单位获取日期差异

我要在几小时内区分当前日期和存储在数据库中的日期.在PostgreSQL中,我可以使用以下查询来完成它:

SELECT storage_time, extract(epoch from (localtimestamp - storage_time))/3600 as diff_hour FROM some_table;

这给了我以小时为单位的日期差异:

      storage_time       |     diff_hour      
-------------------------+-------------------
 2014-02-03 19:37:39.481 |  44.4788805811111
 2014-02-03 19:40:28.201 |  44.4320139144444
 2014-01-29 18:25:12.828 |  165.686284192222
 2014-02-03 19:25:56.861 |  44.6740528033333
 2014-02-05 15:53:38.178 | 0.212575858888889
 2014-01-30 15:53:38.61  |  144.212455858889

现在,我面临着将其移植到Hibernate查询语言的困难.我尝试了很多变化,但我无法从日期差异中获得时代.这肯定不起作用:

"FROM SomeEntity " +
"WHERE someAttribute = :attr " +
"AND epoch(localtimestamp - deviceInfo.storageTime) / 3600 > :threshold_hour";

当我运行此命令时,我得到以下异常:

org.hibernate.exception.SQLGrammarException: could not extract ResultSet
    at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2102)
    at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1835)
    at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:257)
    at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:500)
    at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:388)
    at org.postgresql.jdbc2.AbstractJdbc2Statement.executeQuery(AbstractJdbc2Statement.java:273)
    at org.apache.commons.dbcp.DelegatingPreparedStatement.executeQuery(DelegatingPreparedStatement.java:93)
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:56)
    at org.hibernate.loader.Loader.getResultSet(Loader.java:2040)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1837)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1816)
    at org.hibernate.loader.Loader.doQuery(Loader.java:900)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:342)
    at org.hibernate.loader.Loader.doList(Loader.java:2526)
    at org.hibernate.loader.Loader.doList(Loader.java:2512)
    at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2342)
    at org.hibernate.loader.Loader.list(Loader.java:2337)
    at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:495)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:357)
    at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:195)
    at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1275)
    at org.hibernate.internal.QueryImpl.list(QueryImpl.java:101)

我像这样运行查询:

Query query = sessionFactory.getCurrentSession()
                    .getNamedQuery(GET_NON_EXPIRED_ENTITY)
                    .setString("attr", attr)
                    .setInteger("threshold_hour", thresholdHour);

List instances = query.list();

我打电话的时候,第2行会出现例外情况list().

但是,当我改变epoch()函数时day(),在hibernate查询中,它运行无异常,但当然有意想不到的结果.

有什么方法可以在HQL中获得PostgreSQL查询的相同行为吗？