try {
    Session sess = HibernateSession.currentSession();
    String querystring = "from Usr as usr where usr.usrloginname in ( " +
                                    " select distinct message.usr.usrloginname from Message as message where " +
                                    " message.creationdate between :startdate and :enddate ) ";
    Query q = sess.createQuery(querystring);
    Date startdate = new GregorianCalendar(2003, 2, 18).getTime();
    Date enddate = new GregorianCalendar(2003, 2, 29).getTime();
    q.setParameter("startdate", startdate);
    q.setParameter("enddate", enddate);
    Iterator it = q.iterate();
    while (it.hasNext()) {
        Usr usr = (Usr)it.next();
        log.info(usr.getUsrloginname());
    }
} catch (Exception e) {
    log.error(e);   
} finally {
    try {
        HibernateSession.closeSession();
    } catch (Exception e) {
        log.error(e);
    }
}