14.12. The group by clause
A query that returns aggregate values can be grouped by any property of a returned class or components:
select cat.color, sum(cat.weight), count(cat) from Cat cat group by cat.color
select foo.id, avg(name), max(name) from Foo foo join foo.names name group by foo.id
A
having
clause is also allowed.
select cat.color, sum(cat.weight), count(cat) from Cat cat group by cat.color having cat.color in (eg.Color.TABBY, eg.Color.BLACK)
SQL functions and aggregate functions are allowed in the
having
and order by
clauses if they are supported by the underlying database (i.e., not in MySQL).
select cat from Cat cat join cat.kittens kitten group by cat.id, cat.name, cat.other, cat.properties having avg(kitten.weight) > 100 order by count(kitten) asc, sum(kitten.weight) desc
Neither the
group by
clause nor the order by
clause can contain arithmetic expressions. Hibernate also does not currently expand a grouped entity, so you cannot write group by cat
if all properties of cat
are non-aggregated. You have to list all non-aggregated properties explicitly.