not allowed truncated value in group by [criteria API]? - jpa

Question

I have a query like :
select name, trunc( date, 'MM' ), sum( number )
from t$mytable
group by name, trunc( date, 'MM' );
which runs perfectly, and gives expected result.
I implemented exactly the same query in JPA criteria API :
CriteriaBuilder criteriaBuilder = em.getCriteriaBuilder();
CriteriaQuery criteriaQuery = criteriaBuilder.createQuery( pClass );
Metamodel metamodel = em.getMetamodel();
EntityType entityType_ = metamodel.entity( pClass );
Root<?> root = criteriaQuery.from( pClass );
Expression pathName = root.get( entityType_.getSingularAttribute( "name" ));
Path pathDate = root.get( entityType_.getSingularAttribute( "date" ) );
Expression<Date> pathTruncatedDate = criteriaBuilder.function("trunc", Date.class , pathDate, 'MM');
Expression pathNumber = criteriaBuilder.sum( root.get( entityType_.getSingularAttribute("number") ));
criteriaQuery.select( criteriaBuilder.array( pathName, pathTruncatedDate, pathNumber) );
List<Expression> groupBy = new ArrayList<Expression>();
groupBy.add( pathName);
groupBy.add( pathTruncatedDate);
criteriaQuery.groupBy( groupBy );
TypedQuery<Object[]> q = em.createQuery( criteriaQuery );
<-- and surprisingly I got ORA-00979: not a GROUP BY expression by running it. What coused the problem, everything is on right place, i guess.
Thank You very much in advance!

Answer 1

it's not look like Oracle question but,
what about creating view by your statement and using view in your application?
something like
create view vw_my_table as
select name, trunc( date, 'MM' ), sum( number )
from t$mytable
group by name, trunc( date, 'MM' );

Answer 2

I have same issue and have found the root cause of this ORA-00979.
Oracle automatically handle aggregation of date in below query
select name, trunc( date, 'MM' ), sum( number )
from t$mytable
group by name, trunc( date, 'MM' );
With Criteria API you need to use criteria builder least method.
In your cas you just need to replace select line with:
criteriaQuery.select( criteriaBuilder.array( pathName, criteriaBuilder.least(pathTruncatedDate), pathNumber) );