inner-join query in Hibernate - sql

Question

I want to run a query with Hibernate, but I don't know what I'm donig wrong that I get errors.
I tried following
public List<String> findCourseForStudent(String pnr) {
factory = new Configuration().configure().buildSessionFactory();
Session session = factory.openSession();
Transaction tx = null;
try {
tx = session.beginTransaction();
String sql = "select Course.name from Course inner join CourseMaterial "
+ "on CourseMaterial.course_id = Course.id inner join CourseParticipantship "
+ "on CourseMaterial.id = CourseParticipantship.courseMaterial_id inner join Student "
+ "on Student.id=CourseParticipantship.student_id where Student.personalNumber='" + pnr + "'";
SQLQuery query = session.createSQLQuery(sql);
query.setResultTransformer(Criteria.ALIAS_TO_ENTITY_MAP);
query.setParameter("pnr", pnr);
List data = query.list();
tx.commit();
return data;
} catch(HibernateException e) {
if(tx != null) tx.rollback();
e.printStackTrace();
} finally {
session.close();
}
return null;
}
but I get the following error:
net.sf.ehcache.CacheException: Another unnamed CacheManager already exists in the same VM. Please provide unique names for each CacheManager in the config or do one of following:
1. Use one of the CacheManager.create() static factory methods to reuse same CacheManager with same name or create one if necessary
2. Shutdown the earlier cacheManager before creating new one with same name.
The source of the existing CacheManager is: DefaultConfigurationSource [ ehcache.xml or ehcache-failsafe.xml ]
I've searched for the error and tried some of the solutions, but none of them worked for me, so I tried to use HQL instead of using sql directly, but still no success :(
I don't actually know how to use INNER_JOIN in DetachedCriteria otherwise I think using DetachedCriteria I won't get any errors because I tried to use it for simpler queries and it worked fine.
Following is an example for a simple query that works fine, but I don't know how to wirte it for innerjoin queries
public List<Student> findForCourse(Integer integer) {
DetachedCriteria criteria = DetachedCriteria.forClass(Student.class);
criteria.add(Restrictions.eq("course.id", integer));
criteria.add(Restrictions.ne("active", Boolean.FALSE));
return getHibernateTemplate().findByCriteria(criteria);
}

Answer 1

Finally, I found out how to write my query in hibernate
public List<String> findCourseForStudent(String pnr) {
return jdbcTemplate.query(
"select Course.name from Course inner join CourseMaterial "
+ "on CourseMaterial.course_id = Course.id inner join CourseParticipantship "
+ "on CourseMaterial.id = CourseParticipantship.courseMaterial_id inner join thd.dbo.Student "
+ "on Student.id=CourseParticipantship.student_id where Student.personalNumber= ?", new Object[] { pnr }, new RowMapper() {
public Object mapRow(ResultSet rs, int row) throws SQLException {
return rs;
}
});
}