hql中String类型的日期比较方式

String hql="select vt,u from Vote vt inner join vt.users u where vt.users.userId not in(?) and vt.createdate between ? and ? and vt.type=1 order by vt.voteId desc";
query=session.createQuery(hql);
query.setInteger(0, uid);
query.setString(1, startTime);
query.setString(2, endTime);