JPA read data from database example

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JPA read data from database example

In this section, you will learn how to retrieve data from database using JPA.

In this section, you will learn how to retrieve data from database using JPA.

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.

  1. Again, you create a "JPARead.java" file

  2. Put the following text in this file.

  3. 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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