hibernate entity


hibernate entity

In this section, you will learn about entity in Hibernate.

In this section, you will learn about entity in Hibernate.

hibernate entity

In this section, you will learn about entity in Hibernate.

What is entity ?

In a persistent storage mechanism, an entity is a business object. Example of entities/business objects are employee, department etc. In simplified words, a relational database is known as persistent storage mechanism. Each entity has a associated table in a rational database, each instance of the entity represents a row in this table.

Rules of writing entity class :

Since entity class is an annotated  POJO(Plain old java object), during writing the following points must be keep in mind :

  • must contain constructor.

  • should have getter setter for each field.

  • should not have static or final fields.


In the below example, you will learn about how you can implement entity in hibernate :

Database Table: student

CREATE TABLE `student` ( 
	`id` int(11) NOT NULL auto_increment, 
	`sname` varchar(100) NOT NULL, 
	`sroll` int(11) NOT NULL, 
	`scourse` varchar(10) NOT NULL, 
	PRIMARY KEY (`id`) 

Model Java Class : Student.java

package roseindia;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
import javax.persistence.Table;


public class Student {

	private int id;
	* @return the id
	public int getId() {
	return id;
	* @param id the id to set
	public void setId(int id) {
	this.id = id;
	@Column(name="sname", length=100,nullable=false)
	private String sname;
	* @return the sname
	public String getSname() {
	return sname;
	* @param sname the sname to set
	public void setSname(String sname) {
		this.sname = sname;
	private int sroll;
	* @return the sroll
	public int getSroll() {
		return sroll;
	* @param sroll the sroll to set
	public void setSroll(int sroll) {
	this.sroll = sroll;
	private String scourse;
	* @return the scourse
	public String getScourse() {
		return scourse;
	* @param scourse the scourse to set
	public void setScourse(String scourse) {
		this.scourse = scourse;


Main Class: JPASetParameterNamedParameter.java

package roseindia;

import java.util.Iterator;

import java.util.List;

import javax.persistence.EntityManager;

import javax.persistence.EntityManagerFactory;

import javax.persistence.EntityTransaction;

import javax.persistence.Persistence;

import javax.persistence.Query;

public class JPASetParameterNamedParameter {

	public static void main(String[] args) {
	// TODO Auto-generated method stub
	EntityManagerFactory emf=Persistence.createEntityManagerFactory("jpa");
	EntityManager em=emf.createEntityManager();
	EntityTransaction entr=em.getTransaction();
	Query query=em.createQuery("SELECT st FROM Student st WHERE st.sroll > :roll");
	query.setParameter("roll", 100);
	List results = query.getResultList();
	Iterator stIterator=results.iterator();
	Student st=(Student)stIterator.next();
	System.out.print(" sroll:"+st.getSroll());
	System.out.print(" scourse:"+st.getScourse());
	System.out.println("Record not found.");



log4j:WARN No appenders could be found for logger (org.hibernate.cfg.annotations.Version).

log4j:WARN Please initialize the log4j system properly.

Hibernate: select student0_.id as id0_, student0_.scourse as scourse0_, student0_.sname as sname0_, student0_.sroll as sroll0_ from student student0_ where student0_.sroll>?

sname:Arindam sroll:101 scourse:MCA

sname:Ajay sroll:102 scourse:B.Tech.

sname:Rakesh sroll:103 scourse:B.Tech

sname:Vikas sroll:104 scourse:BCA