Inheritance Type JOINED
File: BadProfessor.java import javax.persistence.Column; import javax.persistence.Entity; @Entity public class BadProfessor extends CompanyProfessor { private long salary; @Column(name="PENSION") private long pensionContribution; public long getPensionContribution() { return pensionContribution; } public void setPensionContribution(long pension) { this.pensionContribution = pension; } public long getSalary() { return salary; } public void setSalary(long salary) { this.salary = salary; } public String toString() { return "FullTimeProfessor id: " + getId() + " name: " + getName(); } } File: CompanyProfessor.java import javax.persistence.Entity; import javax.persistence.Inheritance; import javax.persistence.InheritanceType; import javax.persistence.Table; @Entity @Table(name="COMPANY_EMP") @Inheritance(strategy=InheritanceType.SINGLE_TABLE) public abstract class CompanyProfessor extends Professor { private int vacation; public int getVacation() { return vacation; } public void setVacation(int vacation) { this.vacation = vacation; } } File: Professor.java import java.util.Date; import javax.persistence.Column; import javax.persistence.DiscriminatorColumn; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.Inheritance; import javax.persistence.InheritanceType; import javax.persistence.Table; import javax.persistence.Temporal; import javax.persistence.TemporalType; @Entity @Table(name="EMP") @Inheritance(strategy=InheritanceType.JOINED) @DiscriminatorColumn(name="EMP_TYPE") public abstract class Professor { @Id private int id; private String name; @Temporal(TemporalType.DATE) @Column(name="S_DATE") private Date startDate; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Date getStartDate() { return startDate; } public void setStartDate(Date startDate) { this.startDate = startDate; } public String toString() { return "Professor id: " + getId() + " name: " + getName(); } } File: ProfessorService.java import java.util.Collection; import javax.persistence.EntityManager; import javax.persistence.Query; public class ProfessorService { protected EntityManager em; public ProfessorService(EntityManager em) { this.em = em; } public void createProfessor(Professor emp) { em.persist(emp); } public Collection<Professor> findAllProfessors() { Query query = em.createQuery("SELECT e FROM Professor e"); return (Collection<Professor>) query.getResultList(); } } File: JPAUtil.java import java.io.Reader; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; public class JPAUtil { Statement st; public JPAUtil() throws Exception{ Class.forName("org.hsqldb.jdbcDriver"); System.out.println("Driver Loaded."); String url = "jdbc:hsqldb:data/tutorial"; Connection conn = DriverManager.getConnection(url, "sa", ""); System.out.println("Got Connection."); st = conn.createStatement(); } public void executeSQLCommand(String sql) throws Exception { st.executeUpdate(sql); } public void checkData(String sql) throws Exception { ResultSet rs = st.executeQuery(sql); ResultSetMetaData metadata = rs.getMetaData(); for (int i = 0; i < metadata.getColumnCount(); i++) { System.out.print("\t"+ metadata.getColumnLabel(i + 1)); } System.out.println("\n----------------------------------"); while (rs.next()) { for (int i = 0; i < metadata.getColumnCount(); i++) { Object value = rs.getObject(i + 1); if (value == null) { System.out.print("\t "); } else { System.out.print("\t"+value.toString().trim()); } } System.out.println(""); } } } File: Main.java import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; public class Main { public static void main(String[] a) throws Exception { JPAUtil util = new JPAUtil(); EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService"); EntityManager em = emf.createEntityManager(); ProfessorService service = new ProfessorService(em); em.getTransaction().begin(); BadProfessor emp2 = new BadProfessor(); emp2.setId(2); emp2.setName("bad"); service.createProfessor(emp2); System.out.println("Professors: "); for (Professor emp1 : service.findAllProfessors()) { System.out.print(emp1); } util.checkData("select * from EMP"); em.getTransaction().commit(); em.close(); emf.close(); } } File: persistence.xml <persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence" version="1.0"> <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL"> <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/> <property name="hibernate.hbm2ddl.auto" value="update"/> <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/> <property name="hibernate.connection.username" value="sa"/> <property name="hibernate.connection.password" value=""/> <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/> </properties> </persistence-unit> </persistence>