Named Query example

Instead of writing queries in the main program wherer they are executed, hibernate provides us with a way where we can write queries in the entity class using the annotation "@NamedQuery". The @NamedQuery annotation takes 2 parameters. One is the name of the query using which it should be called and the next is the query. Below is a sample program which explains how to use a named query.

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

    <session-factory>

        <!-- Database connection settings -->
        <property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
        <property name="connection.url">jdbc:oracle:thin:@localhost:1521:xe</property>
        <property name="connection.username">hr</property>
        <property name="connection.password">hr</property>

        <!-- JDBC connection pool (use the built-in) -->
        <property name="connection.pool_size">1</property>

        <!-- SQL dialect -->
        <property name="dialect">org.hibernate.dialect.OracleDialect</property>

        <!-- Disable the second-level cache  -->
        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>

        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">true</property>

        <!-- Drop and re-create the database schema on startup -->
        <property name="hbm2ddl.auto">create</property>

        <!-- Names the annotated entity class -->
        <mapping class="com.ram.dao.Student"/>

    </session-factory>

</hibernate-configuration>

File: com.ram.dao.Student.java

package com.ram.dao;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.NamedQuery;

@Entity
@NamedQuery(name="Student.Id",query="from Student where studentId > ?")
public class Student {
 @Id @GeneratedValue
 private int studentId;
 private String studentName;
 
 public int getStudentId() {
  return studentId;
 }
 public void setStudentId(int studentId) {
  this.studentId = studentId;
 }
 public String getStudentName() {
  return studentName;
 }
 public void setStudentName(String studentName) {
  this.studentName = studentName;
 }
}

File: com.ram.hibernate.HQLParameterExample.java

package com.ram.hibernate;

import java.util.List;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

import com.ram.dao.Student;

public class NamedQueryExample {
 public static void main(String[] args) {
  SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
  Session session = sessionFactory.openSession();
  session.beginTransaction();
  
  Query query = session.getNamedQuery("Student.Id");
  query.setInteger(0, 3);
  List<Student> students = (List<Student>) query.list();
  
  for(Student stud: students){
   System.out.print("Student Id : "+stud.getStudentId());
   System.out.println("Student Name: "+stud.getStudentName());
  }
  
  session.getTransaction().commit();
  session.close();
 }
}

Execute NamedQueryExample.java and you get the output as shown below.