suppose Object A has a list of Object B, and Object B must have a object C, B can be order base on C.level .

In A.hbm.xml

<bag name="listB"
table="T_B"
inverse="false"
order-by="ID_B"
>
<key column="ID_A" not-null="true"/>
<many-to-many column="ID_B" class="B"/>
</bag>

in the order-by, can we put SQL query? or HQL query???

use Criteria API for ordering
Code:
Client user = new Client();
Session session = HibernateUtil.beginTransaction();
Criteria criteria = session.createCriteria(Client.class);
Order order = Order.asc("clientID");
criteria.addOrder(order);
List results = criteria.list();
HibernateUtil.commitTransaction();
for (int i = 0; i<results.size(); i++) {
System.out.println(results.get(i).toString());
}
}


or a simple orderby in the HQL:

Code:
Session session = HibernateUtil.beginTransaction();
String hql = "from Client as cln ORDER BY u.clientId ASC";
Query query = session.createQuery(hql);
List client= query.list();
for (int i = 0; i < client.size(); i++) {
Client cln = (Client) client.get(i);
System.out.println(cln.getName());
}
HibernateUtil.commitTransaction();