@Test public void testQueryFromSub() { for (int i = 0; i < 10; i++) { Person person = randomPerson(); person.setAge(i + 1); data.insert(person); } Integer result = data.select(NamedExpression.ofInteger("avg_age").avg()) .from(data.select(Person.AGE.sum().as("avg_age")).groupBy(Person.AGE).as("t1")) .get() .first() .get(0); assertTrue(result >= 5); // derby rounds up }