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<deftable>
resin-web.xml configuration
persistence.xml configuration
The student bean
The house bean
The course servlet
</deftable> @Entity public class House { @Id @Column(name="id") public long getId() @Basic public String getName() @OneToMany(targetEntity=Student.class, mappedBy="house") public Collection getStudentList() } @Entity public class Student { @Id @Column(name="id") public long getId() @Basic public String getName() @ManyToOne @JoinColumn(name="house") public House getHouse() } private void doService(PrintWriter out) throws java.io.IOException { Query allHouse = _entityManager.createQuery("SELECT o FROM House o"); String sql = ("SELECT s" + " FROM House h, IN(h.studentList) s" + " WHERE h.id=?1 AND s.gender='M'"); Query boysInHouse = _entityManager.createQuery(sql); List houses = allHouse.getResultList(); for (int i = 0; i < houses.size(); i++) { House house = (House) houses.get(i); out.println("<H3>Boys living in " + house.getName() + ":</H3>"); boysInHouse.setParameter(1, new Long(house.getId())); List boys = boysInHouse.getResultList(); if (boys.size() == 0) out.println("No boys are living in " + house.getName()); for (int j = 0; j < boys.size(); j++) { Student boy = (Student) boys.get(j); out.println(boy.getName() + "<br>"); } } } }
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