Design patterns on Spring Hibernate

[redcode7000]

hellow guys, currently I'm creating web application based on spring + hibernate. I just have some question regarding the design patterns of using DAO layer.

So lets say I have two tables, Student table and Subject table. Then I have 2 DAO to perform crud operations with the table.

The DAO layer :

for student;

public class StudentDaoImpl implements StudentDao {
        
         @Autowired
         private SessionFactory sessionFactory;
         public Student getStudeByPk(string studentid){
         // load instance of student
         return sessionFactory.getCurrentSession().load(Student.class, studentid);
         }          
         
         public void saveStudent(Student student){
         sessionFactor.getCurrentSession.save(student);
         }
}

for subject:

public class SubjectDaoImpl implements SubjectDao {
        
         @Autowired
         private SessionFactory sessionFactory;

         public Subject getSubjectByPk(string subjectId){
         // load instance of subject
         return sessionFactory.getCurrentSession().load(Subject.class, subjectId);
         }          
         
         public void saveSubject(Subject subject){
         sessionFactor.getCurrentSession.save(subject);
         }
}

So as you can see, both dao performs direct access to single table.

My question is what if I want to join two tables? what approach do I need to do in order to do that?

Any help would be appreciated!

[Amezick]

This is actually a hibernate issue for you. You need to link the two objects together(1toM or MtoM) and then create a query that manipulates that relationship.

All student that have taken a certain subject:
"from student where student.subject.id = 5"

or if you have a subject object:
Query q = session.createQuery("from student where student.subject = :subject");
q.setEntity("subject",subject);
return q.list();