There is no easy answer to your question. I have given a couple of talks on that topic. Sometimes there are good reasons to have both in a project.
Edit: IMHO Abstraction over the database in regards of dialects and datatypes is not the main point here!! jOOQ does a pretty good job to generate SQL for a given target dialect - and so does JPA / Hibernate. I would even say that jOOQ goes an extra mile to emulate functions for databases that don't have all the bells and whistles like Postgres or Oracle.
The question here is "Do I want to be able to express a query myself with everything SQL has to offer or am I happy with what JPA can express?"
Here's an example to run both together. I have a Spring Data JPA provided repository here with a custom extension (interface and implementation are necessary). I let the Spring context inject both the JPA EntityManager
as well as the jOOQ context. I then use jOOQ to create queries and run them through JPA.
Why? Because expressing the query in question is not possible with JPA ("Give me the thing I listened the most" which is not the one having the highest number of count, but could be several).
The reason I run the query through JPA is simple: A downstream use case might require me to pass JPA entities to it. jOOQ can of course run this query itself and you could work on records or map the stuff anyway u like. But as you specifically asked about maybe using both technologies, I thought this is a good example:
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.Query;
import org.jooq.DSLContext;
import org.jooq.Field;
import org.jooq.Record;
import org.jooq.SelectQuery;
import org.jooq.conf.ParamType;
import org.jooq.impl.DSL;
import org.springframework.data.repository.CrudRepository;
import static ac.simons.bootiful_databases.db.tables.Genres.GENRES;
import static ac.simons.bootiful_databases.db.tables.Plays.PLAYS;
import static ac.simons.bootiful_databases.db.tables.Tracks.TRACKS;
import static org.jooq.impl.DSL.count;
import static org.jooq.impl.DSL.rank;
import static org.jooq.impl.DSL.select;
public interface GenreRepository extends
CrudRepository<GenreEntity, Integer>, GenreRepositoryExt {
List<GenreEntity> findAllByOrderByName();
}
interface GenreRepositoryExt {
List<GenreWithPlaycount> findAllWithPlaycount();
List<GenreEntity> findWithHighestPlaycount();
}
class GenreRepositoryImpl implements GenreRepositoryExt {
private final EntityManager entityManager;
private final DSLContext create;
public GenreRepositoryImpl(EntityManager entityManager, DSLContext create) {
this.entityManager = entityManager;
this.create = create;
}
@Override
public List<GenreWithPlaycount> findAllWithPlaycount() {
final Field<Integer> cnt = count().as("cnt");
return this.create
.select(GENRES.GENRE, cnt)
.from(PLAYS)
.join(TRACKS).onKey()
.join(GENRES).onKey()
.groupBy(GENRES.GENRE)
.orderBy(cnt)
.fetchInto(GenreWithPlaycount.class);
}
@Override
public List<GenreEntity> findWithHighestPlaycount() {
/*
select id, genre
from (
select g.id, g.genre, rank() over (order by count(*) desc) rnk
from plays p
join tracks t on p.track_id = t.id
join genres g on t.genre_id = g.id
group by g.id, g.genre
) src
where src.rnk = 1;
*/
final SelectQuery<Record> sqlGenerator =
this.create.select()
.from(
select(
GENRES.ID, GENRES.GENRE,
rank().over().orderBy(count().desc()).as("rnk")
).from(PLAYS)
.join(TRACKS).onKey()
.join(GENRES).onKey()
.groupBy(GENRES.ID, GENRES.GENRE)
).where(DSL.field("rnk").eq(1)).getQuery();
// Retrieve sql with named parameter
final String sql = sqlGenerator.getSQL(ParamType.NAMED);
// and create actual hibernate query
final Query query = this.entityManager.createNativeQuery(sql, GenreEntity.class);
// fill in parameter
sqlGenerator.getParams().forEach((n, v) -> query.setParameter(n, v.getValue()));
// execute query
return query.getResultList();
}
}
I spoke about this a couple of times. There is no silver bullet in those tech, sometimes it's a very thin judgement:
The full talk is here: https://speakerdeck.com/michaelsimons/live-with-your-sql-fetish-and-choose-the-right-tool-for-the-job
As well as the recorded version of it: https://www.youtube.com/watch?v=NJ9ZJstVL9E
The full working example is here https://github.com/michael-simons/bootiful-databases.