To delete a record from database, EntityManager interface provides remove() method. The remove() method uses primary key to delete the particular record.
JPA Entity Delete Example
Here, we will remove the particular record of the student.
This example contains the following steps: -
1. Create an entity class named as StudentEntity.java under com.javahubpoint.jpa.student package that contains attributes s_id, s_name and s_age.
StudentEntity.java
package com.javahubpoint.jpa.student;
import javax.persistence.*;
@Entity
@Table(name="student")
public class StudentEntity {
@Id
private int s_id;
private String s_name;
private int s_age;
public StudentEntity(int s_id, String s_name, int s_age) {
super();
this.s_id = s_id;
this.s_name = s_name;
this.s_age = s_age;
}
public StudentEntity() {
super();
}
public int getS_id() {
return s_id;
}
public void setS_id(int s_id) {
this.s_id = s_id;
}
public String getS_name() {
return s_name;
}
public void setS_name(String s_name) {
this.s_name = s_name;
}
public int getS_age() {
return s_age;
}
public void setS_age(int s_age) {
this.s_age = s_age;
}
}
2. Now, map the entity class and other databases configuration in Persistence.xml file.
Persistence.xml
<persistence>
<persistence-unit name="Student_details">
<class>com.javahubpoint.jpa.student.StudentEntity</class>
<properties>
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/studentdata"/>
<property name="javax.persistence.jdbc.user" value="root"/>
<property name="javax.persistence.jdbc.password" value=""/>
<property name="eclipselink.logging.level" value="SEVERE"/>
<property name="eclipselink.ddl-generation" value="create-or-extend-tables"/>
</properties>
</persistence>
3. Deletion.java
import javax.persistence.*;
import com.javahubpoint.jpa.student.*;
public class DeleteStudent {
public static void main(String args[])
{
EntityManagerFactory emf=Persistence.createEntityManagerFactory("Student_details");
EntityManager em=emf.createEntityManager();
em.getTransaction().begin();
StudentEntity s=em.find(StudentEntity.class,102);
em.remove(s);
em.getTransaction().commit();
emf.close();
em.close();
}
}
Output:
After the execution of the program, the student table is generated under MySQL workbench. This table contains the student details. To fetch data, run select * from student query in MySQL.
Before Deletion
After Deletion
