14.8. Polymorphic queries

A query like:
from Cat as cat
returns instances not only of Cat, but also of subclasses like DomesticCat. Hibernate queries may name any Java class or interface in the from clause. The query will return instances of all persistent classes that extend that class or implement the interface. The following query would return all persistent objects:
from java.lang.Object o
The interface Named might be implemented by various persistent classes:
from Named n, Named m where n.name = m.name
Note that these last two queries will require more than one SQL SELECT. This means that the order by clause does not correctly order the whole result set. (It also means you can't call these queries using Query.scroll().)