Hql中比较时间时拼hql语句，可以【cast "2010-07-03 10:26:46" as date 】但不能【cast "2010-07-03 10:26:46" as datetime 】，因为hibernate不支持，见如下：
Java代码 String beginDate = "2010-07-03 10:26:46"; String hql = "flowDefinition.createTime > " + "cast('" + beginDate + "' as datetime)" ; String beginDate = "2010-07-03 10:26:46"; String hql = "flowDefinition.createTime > " + "cast('" + beginDate + "' as datetime)" ;但是如果必须比较datetime,可以这样比较：
Java代码 String beginDate = "2010-07-03 10:26:46"; String hql = "flowDefinition.createTime > " + "'"+beginDate+"'" ; String beginDate = "2010-07-03 10:26:46"; String hql = "flowDefinition.createTime > " + "'"+beginDate+"'" ;如果使用sql,mysql同时支持【cast "2010-07-03 10:26:46" as date 】和【cast "2010-07-03 10:26:46" as datetime 】。
