hb : HCQL(Projections)

HCQL (Hibernate Criteria Query Language)

public Criteria setProjection(Projection projection) specifies the projection.

       ProjectionList p1=Projections.projectionList();

       p1.add(Projections.property("name"));

       p1.add(Projections.property("salary"));       

       cr.setProjection(p1);

Employee.java

=========

package mypack;

import javax.persistence.*;

@Entity

@Table(name = "MYEMP")

public class Employee {

@Id

private int id;

private String name;

private float salary;

private String address;

public Employee() {

          super();

}

public Employee(String name, float salary,String address) {

          super();

          this.name = name;

          this.salary = salary;

        this.address = address;

}

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 float getSalary() {

          return salary;

}

public void setSalary(float salary) {

          this.salary = salary;

}

    public String getAddress() {

        return address;

    }

    public void setAddress(String address) {

        this.address = address;

    }

}

hibernate.cfg.xml

===========

<?xml version='1.0' encoding='UTF-8'?>

<!DOCTYPE hibernate-configuration PUBLIC

          "-//Hibernate/Hibernate Configuration DTD 3.0//EN"

          "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

    <session-factory>

        <property name="connection.driver_class">org.apache.derby.jdbc.ClientDriver</property>       

        <property name="dialect">org.hibernate.dialect.DerbyDialect</property>

        <property name="connection.url">jdbc:derby://localhost:1527/myhb</property>

        <property name="connection.username">app</property>

        <property name="connection.password">app</property>

        <property name="show_sql">true</property>

        <property name="hbm2ddl.auto">update</property>  

        <mapping class="mypack.Employee"/>

    </session-factory>

</hibernate-configuration>

SingleProjections.java

==============

package mypack;

import java.util.Iterator;

import java.util.List;

import org.hibernate.*;

import org.hibernate.cfg.*;

import org.hibernate.criterion.Projections;

public class SingleProjection {

public static void main(String[] args) {

       SessionFactory factory =new AnnotationConfiguration().configure().buildSessionFactory();

       Session session=factory.openSession();

       Criteria cr = session.createCriteria(Employee.class);

       cr.setProjection(Projections.property("name"));

       List list = cr.list();

       Iterator itr = list.iterator();

       while(itr.hasNext()){

       String name = (String)itr.next();

       System.out.println(name);

       }      

        session.close();

    }       

}

MultipleProjections.java

===============

package mypack;

import java.util.Iterator;

import java.util.List;

import org.hibernate.*;

import org.hibernate.cfg.*;

import org.hibernate.criterion.ProjectionList;

import org.hibernate.criterion.Projections;

public class MultipleProjections {

public static void main(String[] args) {

       SessionFactory factory =new AnnotationConfiguration().configure().buildSessionFactory();

       Session session=factory.openSession();

       Criteria cr = session.createCriteria(Employee.class);

       ProjectionList p1=Projections.projectionList();

       p1.add(Projections.property("name"));

       p1.add(Projections.property("salary"));       

       cr.setProjection(p1);

       List list = cr.list();

       Iterator itr = list.iterator();

       while(itr.hasNext()){

        Object ob[] = (Object[])itr.next();

          System.out.println(ob[0]+"--------"+ob[1]);

       }      

        session.close();

    }       

}