@Test
public void max() {
EntityManager entityManager = factory.createEntityManager();
CriteriaBuilder builder = entityManager.getCriteriaBuilder();
CriteriaQuery<Integer> query = builder.createQuery(Integer.class);
Root<Employee> root = query.from(Employee.class);
query.select(builder.max(root.get(Employee_.age)));
int min = entityManager.createQuery(query).getSingleResult();
assertEquals(70, min);
}
@Override
protected T beforeInsert(T entity) {
CriteriaBuilder builder = getEntityManager().getCriteriaBuilder();
CriteriaQuery<Long> criteria = builder.createQuery(Long.class);
Root<? extends ChaveValor> productRoot = criteria.from(entity.getClass());
criteria.select(builder.max(productRoot.get("codigo")));
Long codigo = getEntityManager().createQuery(criteria).getSingleResult();
if (codigo == null) {
codigo = 1L;
} else {
codigo++;
}
entity.setCodigo(codigo);
return super.beforeInsert(entity);
}
/** This test provides a demonstration of the MIN and MAX aggregate functions */
@Test
public void testMaxMin() {
log.info("*** testMaxMin() ***");
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<Number> qdef = cb.createQuery(Number.class);
Root<Sale> s = qdef.from(Sale.class);
// select max(s.amount) from Sale s
qdef.select(cb.max(s.<BigDecimal>get("amount")));
List<Number> results = executeQuery(qdef);
assertEquals("unexpected number of rows", 1, results.size());
assertEquals("unexpected result", 150, results.get(0).intValue());
// select min(s.amount) from Sale s
qdef.select(cb.min(s.<BigDecimal>get("amount")));
results = executeQuery(qdef);
assertEquals("unexpected number of rows", 1, results.size());
assertEquals("unexpected result", 100, results.get(0).intValue());
}
/**
* get the last updated timestamp in {@link StopEntity}
*
* @return timeStamp
*/
@SuppressWarnings({"rawtypes", "unchecked"})
@Override
public Date lastUpdate() {
try {
// selectin the table for the required records
CriteriaBuilder criteriaBuilder = getEntityManager().getCriteriaBuilder();
CriteriaQuery<Date> maxQuery = criteriaBuilder.createQuery(Date.class);
Root stopEntityRoot = maxQuery.from(StopEntity.class);
// selecting the records the providing the criteria record with the max timeStamp value
// it should not return multiple records
maxQuery.select(criteriaBuilder.max(stopEntityRoot.<Date>get("timeStamp")));
// to avoid problems only one record is returning here
return getEntityManager().createQuery(maxQuery).getSingleResult();
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
