criteriaquery

In JPA 2, using a CriteriaQuery, how to count results

A query of type MyEntity is going to return MyEntity. You want a query for a Long. CriteriaBuilder qb = entityManager.getCriteriaBuilder(); CriteriaQuery<Long> cq = qb.createQuery(Long.class); cq.select(qb.count(cq.from(MyEntity.class))); cq.where(/*your stuff*/); return entityManager.createQuery(cq).getSingleResult(); Obviously you will want to build up your expression with whatever restrictions and groupings etc you skipped in the example.

JPA Query selecting only specific columns without using Criteria Query?

Yes, like in plain sql you could specify what kind of properties you want to select: SELECT i.firstProperty, i.secondProperty FROM ObjectName i WHERE i.id=10 Executing this query will return a list of Object[], where each array contains the selected properties of one object. Another way is to wrap the selected properties in a custom object … Read more