JPA read data from database example

In this section, you will learn how to retrieve data from database using JPA. Create a "JPARead.java" file and follows the following steps to reading data from database.

Again, you create a "JPARead.java" file
Put the following text in this file.
Read code (JPARead.java):

/**
*
*/
package roseindia;

import java.util.Iterator;
import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.Query;

/**
* @author Administrator
*
*/
public class JPARead {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub

EntityManagerFactory emf = Persistence.createEntityManagerFactory("jpa");
EntityManager em = emf.createEntityManager();
try{
em.getTransaction().begin();
//Select all the record from student table
Query query = em.createQuery("SELECT st FROM Student st");
List lst = query.getResultList();
Iterator it = lst.iterator();
while (it.hasNext()){
Student student = (Student) it.next();
System.out.print("Id:"+student.getId());
System.out.print(" Name:"+student.getSname());
System.out.println(" Course:"+student.getScourse());
}
em.getTransaction().commit();
}
catch(Exception e){
System.out.println(e.getMessage());
}
finally{
em.close();
}
}

}

4.Run and get the output in Console window.

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Comments:2

GhostRider
June 27, 2012
How to connect Remote datastore with JPA?

Hi, How to connect Remote datastore with JPA? Thanks, GhostRider

Panneer
February 6, 2014
em.getTransaction().commit();

Hi , I am new to JPA. Your tutorial is really helpful for new bees. Thank you very much.I would like to have a question. is it mandatory to put em.getTransaction().commit(); for select query also?. Thank you.

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