I can see that the DB4O guys are advancing very well with their object-oriented persistance effort. For example, let me show you this kind of statically typed query:

IList<Student> students = db.Query<Student>(delegate(Student student){
return student.Age < 20
&& student.Grade == gradeA;
});

(Extracted from http://developer.db4o.com/blogs/kudos/archive/2006/12/18/kudo-distributed-employees-all-around-the-world.aspx.)

Does NHibernate support this kind of query to be translated into SQL? If not, what is the most similar way to query like this?

Regards.