Is it possible to use HQL for fields not stored in the Database?

For instance, let's say my object has a method - a getter - which instead of returning a property, runs some calculations. Is there anyway I can use HQL on this method?

Now, I realize that there would be tremendous performance costs for this. How is this normally handled? Can I write the method in SQL - instead of Java - and then have Hibernate use the SQL formula to query? How do I this for subclasses (will Hibernate automatically use that classes SQL forumla)?

As far as I understand the definition of HQL, it only allows to use properties, which are the items defined in the mapping files.

However, you may define derived properties. So if you can express your calculation in an SQL formula, then define a derived property for your purpose. As the calculation can be included in any SQL search that Hibernate issues, your performance qualms are solved.