Java/JPA/ResultSet Mappings

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Версия от 18:01, 31 мая 2010; (обсуждение)
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Cast Result List To Generic Collection

File: Department.java

import java.util.ArrayList;
import java.util.Collection;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
@Entity
public class Department {
    @Id @GeneratedValue(strategy=GenerationType.IDENTITY)
    private int id;
    private String name;
    @OneToMany(targetEntity=Professor.class, mappedBy="department")
    private Collection employees;
    public Department() {
        employees = new ArrayList<Professor>();
    }
    public int getId() {
        return id;
    }
    
    public void setId(int id) {
        this.id = id;
    }
    
    public String getName() {
        return name;
    }
    
    public void setName(String deptName) {
        this.name = deptName;
    }
    
    public void addProfessor(Professor employee) {
        if (!getProfessors().contains(employee)) {
            getProfessors().add(employee);
            if (employee.getDepartment() != null) {
                employee.getDepartment().getProfessors().remove(employee);
            }
            employee.setDepartment(this);
        }
    }
    
    public Collection getProfessors() {
        return employees;
    }
    public String toString() {
        return "Department id: " + getId() + 
               ", name: " + getName();
    }
}

File: Professor.java

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.ManyToOne;
@Entity
public class Professor {
    @Id @GeneratedValue(strategy=GenerationType.IDENTITY)
    private int id;
    private String name;
    private long salary;
    
    @ManyToOne
    private Department department;
    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 long getSalary() {
        return salary;
    }
    public void setSalary(long salary) {
        this.salary = salary;
    }
    
    public Department getDepartment() {
        return department;
    }
    
    public void setDepartment(Department department) {
        this.department = department;
    }
    public String toString() {
        return "Professor id: " + getId() + " name: " + getName() + 
               " with " + getDepartment();
    }
}

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 Department createDepartment(String name) {
    Department dept = new Department();
    dept.setName(name);
    em.persist(dept);
    return dept;
  }
  public Collection<Department> findAllDepartments() {
    Query query = em.createQuery("SELECT d FROM Department d");
    return (Collection<Department>) query.getResultList();
  }
  public Professor createProfessor(String name, long salary) {
    Professor emp = new Professor();
    emp.setName(name);
    emp.setSalary(salary);
    em.persist(emp);
    return emp;
  }
  public Professor setProfessorDepartment(int empId, int deptId) {
    Professor emp = em.find(Professor.class, empId);
    Department dept = em.find(Department.class, deptId);
    dept.addProfessor(emp);
    return emp;
  }
  public Collection<Professor> findAllProfessors() {
    Query query = em.createQuery("SELECT e FROM Professor e");
    return (Collection<Professor>) query.getResultList();
  }
}

File: Main.java
import java.util.Collection;
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();
    Professor emp = service.createProfessor("empName",100);
    Department dept = service.createDepartment("deptName");
    emp = service.setProfessorDepartment(emp.getId(),dept.getId());
    System.out.println(emp.getDepartment() + " with Professors:");
    System.out.println(emp.getDepartment().getProfessors());
    Collection<Professor> emps = service.findAllProfessors();
    if (emps.isEmpty()) {
        System.out.println("No Professors found ");
    } else {
        System.out.println("Found Professors:");
        for (Professor emp1 : emps) {
            System.out.println(emp1);
        }
    }
    
    Collection<Department> depts = service.findAllDepartments();
    if (depts.isEmpty()) {
        System.out.println("No Departments found ");
    } else {
        System.out.println("Found Departments:");
        for (Department dept1 : depts) {
            System.out.println(dept1 + " with " + dept1.getProfessors().size() + " employees");
        }
    }

    util.checkData("select * from Professor");
    util.checkData("select * from Department");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}

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: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/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>





Inheritance Result Mapping

File: ContractProfessor.java
import javax.persistence.Column;
import javax.persistence.Entity;
@Entity
public class ContractProfessor extends Professor {
  @Column(name = "DAILY_RATE")
  private int dailyRate;
  private int term;
  public int getDailyRate() {
    return dailyRate;
  }
  public void setDailyRate(int dailyRate) {
    this.dailyRate = dailyRate;
  }
  public int getTerm() {
    return term;
  }
  public void setTerm(int term) {
    this.term = term;
  }
  public String toString() {
    return "ContractProfessor id: " + getId() + " name: " + getName();
  }
}

File: Professor.java

import java.util.Date;
import javax.persistence.Column;
import javax.persistence.DiscriminatorColumn;
import javax.persistence.Entity;
import javax.persistence.EntityResult;
import javax.persistence.FieldResult;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.SqlResultSetMapping;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
@Entity 
@Table(name="EMPLOYEE")
@Inheritance
@DiscriminatorColumn(name="EMP_TYPE")
@SqlResultSetMapping(
    name="ProfessorStageMapping",
    entities=
        @EntityResult(
            entityClass=Professor.class,
            discriminatorColumn="TYPE",
            fields={
                @FieldResult(name="startDate", column="START_DATE"),
                @FieldResult(name="dailyRate", column="DAILY_RATE"),
                @FieldResult(name="hourlyRate", column="HOURLY_RATE")
            }
        )
)
public abstract class Professor {
    @Id private int id;
    private String name;
    @Temporal(TemporalType.DATE)
    @Column(name="START_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.List;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public List findAllProfessors() {
    Query query = em.createNativeQuery("SELECT id, name, start_date, daily_rate, term "
        + " FROM employee", "ProfessorStageMapping");
    return 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();

    service.findAllProfessors();
    
    util.checkData("select * from Professor");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}


File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/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>





Inheritance Result Mapping Two Subclasses

File: FullTimeProfessor.java

import javax.persistence.DiscriminatorValue;
import javax.persistence.Entity;
@Entity
@DiscriminatorValue("FTEmp")
public class FullTimeProfessor extends Professor {
    private long salary;
    private long pension;
    
    public long getPension() {
        return pension;
    }
    
    public void setPension(long pension) {
        this.pension = pension;
    }
    
    public long getSalary() {
        return salary;
    }
    
    public void setSalary(long salary) {
        this.salary = salary;
    }
    public String toString() {
        return "FullTimeProfessor id: " + getId() + " name: " + getName();
    }
}

File: PartTimeProfessor.java

import javax.persistence.Column;
import javax.persistence.DiscriminatorValue;
import javax.persistence.Entity;
@Entity(name="PTEmp")
@DiscriminatorValue("PTEmp")
public class PartTimeProfessor extends Professor {
    @Column(name="HOURLY_RATE")
    private float hourlyRate;
    public float getHourlyRate() {
        return hourlyRate;
    }
    public void setHourlyRate(float hourlyRate) {
        this.hourlyRate = hourlyRate;
    }
    public String toString() {
        return "PartTimeProfessor id: " + getId() + " name: " + getName();
    }
}

File: Professor.java

import java.util.Date;
import javax.persistence.Column;
import javax.persistence.DiscriminatorColumn;
import javax.persistence.Entity;
import javax.persistence.EntityResult;
import javax.persistence.FieldResult;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.MappedSuperclass;
import javax.persistence.SqlResultSetMapping;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
@Entity 
@Table(name="EMPLOYEE")
@Inheritance
@DiscriminatorColumn(name="EMP_TYPE")
@MappedSuperclass
@SqlResultSetMapping(
    name="ProfessorStageMapping",
    entities=
        @EntityResult(
            entityClass=Professor.class,
            discriminatorColumn="TYPE",
            fields={
                @FieldResult(name="startDate", column="START_DATE"),
                @FieldResult(name="dailyRate", column="DAILY_RATE"),
                @FieldResult(name="hourlyRate", column="HOURLY_RATE")
            }
        )
)
public abstract class Professor {
    @Id private int id;
    private String name;
    @Temporal(TemporalType.DATE)
    @Column(name="START_DATE")
    private Date startDate;
    private int vacation;

    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 int getVacation() {
      return vacation;
  }
  public void setVacation(int vacation) {
      this.vacation = vacation;
  }
    public String toString() {
        return "Professor id: " + getId() + " name: " + getName();
    }
}

File: ProfessorService.java
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public List findAllProfessors() {
    Query query = em.createNativeQuery("SELECT id, name, start_date, vacation "
        + " FROM employee", "ProfessorStageMapping");
    return 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();

    service.findAllProfessors();
    
    util.checkData("select * from Professor");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}



File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/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>





Sql Resultset Mapping: Column Result

File: Address.java
import javax.persistence.Entity;
import javax.persistence.Id;
@Entity
public class Address {
  @Id
  private int id;
  private String street;
  private String city;
  private String state;
  private String zip;
  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }
  public String getStreet() {
    return street;
  }
  public void setStreet(String address) {
    this.street = address;
  }
  public String getCity() {
    return city;
  }
  public void setCity(String city) {
    this.city = city;
  }
  public String getState() {
    return state;
  }
  public void setState(String state) {
    this.state = state;
  }
  public String getZip() {
    return zip;
  }
  public void setZip(String zip) {
    this.zip = zip;
  }
  public String toString() {
    return "Address id: " + getId() + ", street: " + getStreet() + ", city: " + getCity()
        + ", state: " + getState() + ", zip: " + getZip();
  }
}

File: Department.java
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
@Entity
public class Department {
  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private int id;
  private String name;
  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }
  public String getName() {
    return name;
  }
  public void setName(String deptName) {
    this.name = deptName;
  }
  public String toString() {
    return "Department id: " + getId() + ", name: " + getName();
  }
}

File: Professor.java
import java.util.ArrayList;
import java.util.Collection;
import javax.persistence.Column;
import javax.persistence.ColumnResult;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.OneToOne;
import javax.persistence.SqlResultSetMapping;
import javax.persistence.SqlResultSetMappings;
import javax.persistence.Table;
@Entity
@Table(name = "EMP")
@SqlResultSetMappings( {
@SqlResultSetMapping(name = "ProfessorAndManager", columns = { @ColumnResult(name = "EMP_NAME"),
    @ColumnResult(name = "MANAGER_NAME") })
})
public class Professor {
  @Id
  @Column(name = "EMP_ID")
  private int id;
  private String name;
  private long salary;
  @OneToOne
  private Address address;
  @ManyToOne
  @JoinColumn(name = "DEPT_ID")
  private Department department;
  @ManyToOne
  @JoinColumn(name = "MANAGER_ID")
  private Professor manager;
  @OneToMany(mappedBy = "manager")
  private Collection<Professor> directs = new ArrayList<Professor>();
  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 long getSalary() {
    return salary;
  }
  public void setSalary(long salary) {
    this.salary = salary;
  }
  public Address getAddress() {
    return address;
  }
  public void setAddress(Address address) {
    this.address = address;
  }
  public Department getDepartment() {
    return department;
  }
  public void setDepartment(Department department) {
    this.department = department;
  }
  public Collection<Professor> getDirects() {
    return directs;
  }
  public void addDirect(Professor employee) {
    if (!getDirects().contains(employee)) {
      getDirects().add(employee);
      if (employee.getManager() != null) {
        employee.getManager().getDirects().remove(employee);
      }
      employee.setManager(this);
    }
  }
  public Professor getManager() {
    return manager;
  }
  public void setManager(Professor manager) {
    this.manager = manager;
  }
  public String toString() {
    return "Professor id: " + getId() + " name: " + getName() + " with MgrId: "
        + (getManager() == null ? null : getManager().getId());
  }
}

File: ProfessorService.java
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public List findProfessorWithManager() {
    Query query = em.createNativeQuery("SELECT e.name AS emp_name, m.name AS manager_name "
        + "FROM emp e, emp m " + "WHERE e.manager_id = m.emp_id", "ProfessorAndManager");
    return query.getResultList();
  }
}

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();

    service.findProfessorWithManager();
    
    util.checkData("select * from EMP");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}

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: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/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>





SQL Resultset Mapping: One Entity

File: Address.java
import javax.persistence.Entity;
import javax.persistence.Id;
@Entity
public class Address {
  @Id
  private int id;
  private String street;
  private String city;
  private String state;
  private String zip;
  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }
  public String getStreet() {
    return street;
  }
  public void setStreet(String address) {
    this.street = address;
  }
  public String getCity() {
    return city;
  }
  public void setCity(String city) {
    this.city = city;
  }
  public String getState() {
    return state;
  }
  public void setState(String state) {
    this.state = state;
  }
  public String getZip() {
    return zip;
  }
  public void setZip(String zip) {
    this.zip = zip;
  }
  public String toString() {
    return "Address id: " + getId() + ", street: " + getStreet() + ", city: " + getCity()
        + ", state: " + getState() + ", zip: " + getZip();
  }
}

File: Department.java
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
@Entity
public class Department {
  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private int id;
  private String name;
  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }
  public String getName() {
    return name;
  }
  public void setName(String deptName) {
    this.name = deptName;
  }
  public String toString() {
    return "Department id: " + getId() + ", name: " + getName();
  }
}

File: Professor.java
import java.util.ArrayList;
import java.util.Collection;
import javax.persistence.Column;
import javax.persistence.ColumnResult;
import javax.persistence.Entity;
import javax.persistence.EntityResult;
import javax.persistence.FieldResult;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.OneToOne;
import javax.persistence.SqlResultSetMapping;
import javax.persistence.SqlResultSetMappings;
import javax.persistence.Table;
@Entity
@Table(name = "EMP")
@SqlResultSetMappings( {
    @SqlResultSetMapping(name = "employeeResult", entities = @EntityResult(entityClass = Professor.class))
     })
public class Professor {
  @Id
  @Column(name = "EMP_ID")
  private int id;
  private String name;
  private long salary;
  @OneToOne
  private Address address;
  @ManyToOne
  @JoinColumn(name = "DEPT_ID")
  private Department department;
  @ManyToOne
  @JoinColumn(name = "MANAGER_ID")
  private Professor manager;
  @OneToMany(mappedBy = "manager")
  private Collection<Professor> directs = new ArrayList<Professor>();
  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 long getSalary() {
    return salary;
  }
  public void setSalary(long salary) {
    this.salary = salary;
  }
  public Address getAddress() {
    return address;
  }
  public void setAddress(Address address) {
    this.address = address;
  }
  public Department getDepartment() {
    return department;
  }
  public void setDepartment(Department department) {
    this.department = department;
  }
  public Collection<Professor> getDirects() {
    return directs;
  }
  public void addDirect(Professor employee) {
    if (!getDirects().contains(employee)) {
      getDirects().add(employee);
      if (employee.getManager() != null) {
        employee.getManager().getDirects().remove(employee);
      }
      employee.setManager(this);
    }
  }
  public Professor getManager() {
    return manager;
  }
  public void setManager(Professor manager) {
    this.manager = manager;
  }
  public String toString() {
    return "Professor id: " + getId() + " name: " + getName() + " with MgrId: "
        + (getManager() == null ? null : getManager().getId());
  }
}

File: ProfessorService.java
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public List findAllProfessors() {
    Query query = em.createNativeQuery("SELECT emp_id, name, salary, manager_id, "
        + "dept_id, address_id " + "FROM EMP ", "employeeResult");
    return query.getResultList();
  }
}

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();

    service.findAllProfessors();
    
    util.checkData("select * from EMP");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}

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: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/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>





SQL Resultset Mapping: Two Entities

File: Address.java
import javax.persistence.Entity;
import javax.persistence.Id;
@Entity
public class Address {
  @Id
  private int id;
  private String street;
  private String city;
  private String state;
  private String zip;
  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }
  public String getStreet() {
    return street;
  }
  public void setStreet(String address) {
    this.street = address;
  }
  public String getCity() {
    return city;
  }
  public void setCity(String city) {
    this.city = city;
  }
  public String getState() {
    return state;
  }
  public void setState(String state) {
    this.state = state;
  }
  public String getZip() {
    return zip;
  }
  public void setZip(String zip) {
    this.zip = zip;
  }
  public String toString() {
    return "Address id: " + getId() + ", street: " + getStreet() + ", city: " + getCity()
        + ", state: " + getState() + ", zip: " + getZip();
  }
}

File: Department.java
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
@Entity
public class Department {
  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private int id;
  private String name;
  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }
  public String getName() {
    return name;
  }
  public void setName(String deptName) {
    this.name = deptName;
  }
  public String toString() {
    return "Department id: " + getId() + ", name: " + getName();
  }
}

File: Professor.java
import java.util.ArrayList;
import java.util.Collection;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.EntityResult;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.OneToOne;
import javax.persistence.SqlResultSetMapping;
import javax.persistence.SqlResultSetMappings;
import javax.persistence.Table;
@Entity
@Table(name = "EMP")
@SqlResultSetMappings( { @SqlResultSetMapping(name = "ProfessorWithAddress", entities = {
    @EntityResult(entityClass = Professor.class), @EntityResult(entityClass = Address.class) })
})
public class Professor {
  @Id
  @Column(name = "EMP_ID")
  private int id;
  private String name;
  private long salary;
  @OneToOne
  private Address address;
  @ManyToOne
  @JoinColumn(name = "DEPT_ID")
  private Department department;
  @ManyToOne
  @JoinColumn(name = "MANAGER_ID")
  private Professor manager;
  @OneToMany(mappedBy = "manager")
  private Collection<Professor> directs = new ArrayList<Professor>();
  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 long getSalary() {
    return salary;
  }
  public void setSalary(long salary) {
    this.salary = salary;
  }
  public Address getAddress() {
    return address;
  }
  public void setAddress(Address address) {
    this.address = address;
  }
  public Department getDepartment() {
    return department;
  }
  public void setDepartment(Department department) {
    this.department = department;
  }
  public Collection<Professor> getDirects() {
    return directs;
  }
  public void addDirect(Professor employee) {
    if (!getDirects().contains(employee)) {
      getDirects().add(employee);
      if (employee.getManager() != null) {
        employee.getManager().getDirects().remove(employee);
      }
      employee.setManager(this);
    }
  }
  public Professor getManager() {
    return manager;
  }
  public void setManager(Professor manager) {
    this.manager = manager;
  }
  public String toString() {
    return "Professor id: " + getId() + " name: " + getName() + " with MgrId: "
        + (getManager() == null ? null : getManager().getId());
  }
}

File: ProfessorService.java
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public List findProfessorWithAddress() {
    Query query = em.createNativeQuery(
            "SELECT emp_id, name, salary, manager_id, dept_id, address_id, " +
            "id, street, city, state, zip " +
            "FROM emp, address " +
            "WHERE address_id = id",
            "ProfessorWithAddress");
    return query.getResultList();
}
}

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();

    service.findProfessorWithAddress();
    
    util.checkData("select * from EMP");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}

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: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/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>





Sql Resultset Mapping With Alias

File: Address.java
import javax.persistence.Entity;
import javax.persistence.Id;
@Entity
public class Address {
  @Id
  private int id;
  private String street;
  private String city;
  private String state;
  private String zip;
  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }
  public String getStreet() {
    return street;
  }
  public void setStreet(String address) {
    this.street = address;
  }
  public String getCity() {
    return city;
  }
  public void setCity(String city) {
    this.city = city;
  }
  public String getState() {
    return state;
  }
  public void setState(String state) {
    this.state = state;
  }
  public String getZip() {
    return zip;
  }
  public void setZip(String zip) {
    this.zip = zip;
  }
  public String toString() {
    return "Address id: " + getId() + ", street: " + getStreet() + ", city: " + getCity()
        + ", state: " + getState() + ", zip: " + getZip();
  }
}

File: Department.java
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
@Entity
public class Department {
  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private int id;
  private String name;
  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }
  public String getName() {
    return name;
  }
  public void setName(String deptName) {
    this.name = deptName;
  }
  public String toString() {
    return "Department id: " + getId() + ", name: " + getName();
  }
}

File: Professor.java
import java.util.ArrayList;
import java.util.Collection;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.EntityResult;
import javax.persistence.FieldResult;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.OneToOne;
import javax.persistence.SqlResultSetMapping;
import javax.persistence.SqlResultSetMappings;
import javax.persistence.Table;
@Entity
@Table(name = "EMP")
@SqlResultSetMappings( { 
  
  @SqlResultSetMapping(
      name="ProfessorWithAddressColumnAlias",
      entities={@EntityResult(entityClass=Professor.class,
                              fields=@FieldResult(name="id", column="EMP_ID")),
                @EntityResult(entityClass=Address.class)}
  )
})
public class Professor {
  @Id
  @Column(name = "EMP_ID")
  private int id;
  private String name;
  private long salary;
  @OneToOne
  private Address address;
  @ManyToOne
  @JoinColumn(name = "DEPT_ID")
  private Department department;
  @ManyToOne
  @JoinColumn(name = "MANAGER_ID")
  private Professor manager;
  @OneToMany(mappedBy = "manager")
  private Collection<Professor> directs = new ArrayList<Professor>();
  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 long getSalary() {
    return salary;
  }
  public void setSalary(long salary) {
    this.salary = salary;
  }
  public Address getAddress() {
    return address;
  }
  public void setAddress(Address address) {
    this.address = address;
  }
  public Department getDepartment() {
    return department;
  }
  public void setDepartment(Department department) {
    this.department = department;
  }
  public Collection<Professor> getDirects() {
    return directs;
  }
  public void addDirect(Professor employee) {
    if (!getDirects().contains(employee)) {
      getDirects().add(employee);
      if (employee.getManager() != null) {
        employee.getManager().getDirects().remove(employee);
      }
      employee.setManager(this);
    }
  }
  public Professor getManager() {
    return manager;
  }
  public void setManager(Professor manager) {
    this.manager = manager;
  }
  public String toString() {
    return "Professor id: " + getId() + " name: " + getName() + " with MgrId: "
        + (getManager() == null ? null : getManager().getId());
  }
}

File: ProfessorService.java
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public List findWithAlias() {
    Query query = em.createNativeQuery(
        "SELECT emp.emp_id AS emp_id, name, salary, manager_id, dept_id, address_id, "
            + "address.id, street, city, state, zip " + "FROM emp, address "
            + "WHERE address_id = id", "ProfessorWithAddressColumnAlias");
    return query.getResultList();
  }
}

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();

    service.findWithAlias();
    
    util.checkData("select * from EMP");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}

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: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/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>





Using Entity Result

File: Department.java
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
@Entity
public class Department {
  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private int id;
  private String name;
  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }
  public String getName() {
    return name;
  }
  public void setName(String deptName) {
    this.name = deptName;
  }
  public String toString() {
    return "Department id: " + getId() + ", name: " + getName();
  }
}

File: Professor.java
import java.util.ArrayList;
import java.util.Collection;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.EntityResult;
import javax.persistence.FieldResult;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.OneToOne;
import javax.persistence.SqlResultSetMapping;
import javax.persistence.SqlResultSetMappings;
import javax.persistence.Table;
@Entity
@Table(name = "EMP")
@SqlResultSetMappings( { 
  
  @SqlResultSetMapping(
      name="ProfessorWithAddressColumnAlias",
      entities={@EntityResult(entityClass=Professor.class,
                              fields=@FieldResult(name="id", column="EMP_ID")),
                @EntityResult(entityClass=Address.class)}
  )
})
public class Professor {
  @Id
  @Column(name = "EMP_ID")
  private int id;
  private String name;
  private long salary;
  @OneToOne
  private Address address;
  @ManyToOne
  @JoinColumn(name = "DEPT_ID")
  private Department department;
  @ManyToOne
  @JoinColumn(name = "MANAGER_ID")
  private Professor manager;
  @OneToMany(mappedBy = "manager")
  private Collection<Professor> directs = new ArrayList<Professor>();
  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 long getSalary() {
    return salary;
  }
  public void setSalary(long salary) {
    this.salary = salary;
  }
  public Address getAddress() {
    return address;
  }
  public void setAddress(Address address) {
    this.address = address;
  }
  public Department getDepartment() {
    return department;
  }
  public void setDepartment(Department department) {
    this.department = department;
  }
  public Collection<Professor> getDirects() {
    return directs;
  }
  public void addDirect(Professor employee) {
    if (!getDirects().contains(employee)) {
      getDirects().add(employee);
      if (employee.getManager() != null) {
        employee.getManager().getDirects().remove(employee);
      }
      employee.setManager(this);
    }
  }
  public Professor getManager() {
    return manager;
  }
  public void setManager(Professor manager) {
    this.manager = manager;
  }
  public String toString() {
    return "Professor id: " + getId() + " name: " + getName() + " with MgrId: "
        + (getManager() == null ? null : getManager().getId());
  }
}

File: ProfessorService.java
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public List findWithAlias() {
    Query query = em.createNativeQuery(
        "SELECT emp.emp_id AS emp_id, name, salary, manager_id, dept_id, address_id, "
            + "address.id, street, city, state, zip " + "FROM emp, address "
            + "WHERE address_id = id", "ProfessorWithAddressColumnAlias");
    return query.getResultList();
  }
}

File: Address.java
import javax.persistence.Entity;
import javax.persistence.Id;
@Entity
public class Address {
  @Id
  private int id;
  private String street;
  private String city;
  private String state;
  private String zip;
  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }
  public String getStreet() {
    return street;
  }
  public void setStreet(String address) {
    this.street = address;
  }
  public String getCity() {
    return city;
  }
  public void setCity(String city) {
    this.city = city;
  }
  public String getState() {
    return state;
  }
  public void setState(String state) {
    this.state = state;
  }
  public String getZip() {
    return zip;
  }
  public void setZip(String zip) {
    this.zip = zip;
  }
  public String toString() {
    return "Address id: " + getId() + ", street: " + getStreet() + ", city: " + getCity()
        + ", state: " + getState() + ", zip: " + getZip();
  }
}

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();

    service.findWithAlias();
    
    util.checkData("select * from EMP");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}


File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/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>


Источник — «http://jexp.ru/index.php?title=Java/JPA/ResultSet_Mappings&oldid=8954»