Question

I am using hibernate. I need to create query below. It is possible the subContest is null in which case subContest_id=:cont should NOT be part of where clause. In conventional SQL when creating dynamic sql ; for such cases I used to do subContest_id = subContest_id ; BUT how do I achieve it in case below. Here If I try to query.setParameter( "cont", "subContest_id " ); it will give exception as cont is supposed to be an id and not a string.

    Query query = getEntityManager().createQuery( "select * from Upload where moderated=:mod, subContest_id=:cont order by lastModifiedTime desc " );
    query.setParameter( "cont", subContest.getId() );

Answer 1

you can try using criteria query in hibernate

Criteria criteria = session.createCriteria(Upload.class);

you can add your where clause as restrictions

Criteria criteria = session.createCriteria(Upload.class)
    .add(Restrictions.eq("mode", value));

in your case you want to check null before adding restriction

if(subContest_id!=null){
        criteria.add(Expression.le("subContest_id",subContest_id));
    }

and finally order by can be done using this

Criteria criteria = session.createCriteria(Upload.class)
    .addOrder( Order.desc("lastModifiedTime") );

please refer here for details on how to use criteria queries