JPQL statement returning boolean value

select jpa jpa-2.0 jpql
Piotr Sobczyk picture Piotr Sobczyk · Aug 21, 2012 · Viewed 37.8k times · Source

Is it possible to write JPQL query like following:

select count(*) > 0 from Scenario scen where scen.name = :name

that would return true/false boolean values depending of whether entity filling criteria exists or not?

I would like to use the query this way: 

boolean exists = entityManager.createQuery(query,Boolean.class).setParameter("name",name).getSingleResult();

The query from my example just isn't syntactically correct (parse error), but is there any correct way of doing checks like that in JPQL, that would return boolean value, or is it only possible in Java code?

Answer

Mikko Maunu picture Mikko Maunu · Aug 21, 2012

Yes, it is possible with following:

select case when (count(scen) > 0)  then true else false end  
from Scenario scen where scen.name = :name

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