java hibernate criteria projections rowCount only 1 column

Question

i have a hibernate query to check is the alias of a student(user_name) is unique this is working very well this is my code.

public Boolean isAliasUniqueInStudent(String alias) 
{        
    Session session = getHibernateTemplate().getSessionFactory().openSession();        
    ProjectionList p = Projections.projectionList().add(Projections.rowCount());
    org.hibernate.criterion.Conjunction exist=(Conjunction)Restrictions.conjunction().add(Restrictions.isNotNull("username")).add(Restrictions.eq("username",alias));
    Criteria criteria = session().createCriteria(Student.class).setProjection(p).add(exist);               
    Long result=(Long)criteria.uniqueResult();
    closeSession(session);
    return result.intValue()==0;
}

this is creating a select like this.

select count(*) as y0_ from student this_ where (this_.username is not null and this_.username=?)

this is very good but i was wondering is possible try a select like

select count(username) as y0_ from student this_ where (this_.username is not null and this_.username=?)

is this a better approach than mine?

exist a better one?

i know i am checking the property not being null.. but is this possible doing it with hibernate.

select count(name)

thanks a lot.

Answer 1

Have you tried this?

Projections.projectionList().add(Projections.count("username");