HQL Tutorial HQL select, Update And Delete Queries

Last Updated on Dec 28, 2019 by Mukesh Kumar

In this example we are going to see how to use Hibernate Query Language (HQL).

Project Structure :

Create a simple java project in Eclipse, and add hibernate related jar files to the classpath of the project. The final project structure is given below.

Create Model Classes :

Student.java

package com.jwt.hibernate;

public class Student {
	private long id;
	private String name;
	private String degree;
	private String roll;
	private String phone;

	public long getId() {
		return id;
	}

	public void setId(long id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getDegree() {
		return degree;
	}

	public void setDegree(String degree) {
		this.degree = degree;
	}

	public String getRoll() {
		return roll;
	}

	public void setRoll(String roll) {
		this.roll = roll;
	}

	public String getPhone() {
		return phone;
	}

	public void setPhone(String phone) {
		this.phone = phone;
	}

}

Create Hibernate Mapping File :

Create student.hbm.xml file to map the Student class with the database tables.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="com.jwt.hibernate.Student" table="STUDENT">
		<id column="ID" name="id" type="long">
			<generator class="increment" />
		</id>
		<property column="STUDENT_NAME" name="name" type="string" />
		<property column="DEGREE" name="degree" type="string" />
		<property column="ROLL" name="roll" type="string" />
		<property column="PHONE" name="phone" type="string" />
	</class>
</hibernate-mapping>

Create Hibernate Configuration File:

Create the Hibernate configuration file (hibernate.cfg.xml) to specify database type, connection details and the mapping files:

hibernate.cfg.xml

<?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>
	 	<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
		<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/jwt</property>
		<property name="hibernate.connection.username">root</property>
		<property name="hibernate.connection.password">mukesh</property>
		<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
		<property name="show_sql">true</property>
		<property name="format_sql">true</property>
		<property name="hbm2ddl.auto">update </property>
		<mapping resource="com/jwt/hibernate/student.hbm.xml" />
	</session-factory>
</hibernate-configuration>

Program to insert data :

Create the Hibernate configuration file (hibernate.cfg.xml) to specify database type, connection details and the mapping files:

InsertData.java

package com.jwt.hibernate;

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

public class InsertData {

	public static void main(String[] args) {

		Configuration cfg = new Configuration();
		cfg.configure("hibernate.cfg.xml");

		SessionFactory factory = cfg.buildSessionFactory();
		Session session = factory.openSession();
		Student student = new Student();
		student.setName("Ravi");
		student.setRoll("102");
		student.setPhone("8888");
		student.setDegree("B.E");

		Student student1 = new Student();
		student1.setName("Mukesh");
		student1.setRoll("103");
		student1.setPhone("9999");
		student1.setDegree("B.E");

		Transaction tx = session.beginTransaction();
		session.save(student);
		session.save(student1);
		System.out.println("Object saved successfully.....!!");
		tx.commit();
		session.close();
		factory.close();
	}
}

Program to retrieve data

package com.jwt.hibernate;

import java.util.List;

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

public class SimpleSelect {

	public static void main(String[] args) {

		Configuration cfg = new Configuration();
		cfg.configure("hibernate.cfg.xml");

		SessionFactory factory = cfg.buildSessionFactory();
		Session session = factory.openSession();
		Transaction tx = session.beginTransaction();

		// Get All Employees
		Query query = session.createQuery("from Student");
		List<Student> list = (List<Student>) query.list();
		for (Student st : list) {
			System.out.println("List of Employees::" + st.getId() + ","
					+ st.getName() + "," + st.getDegree());
		}
		// Get Employee with id
		query = session.createQuery("from Student where id= :id");
		query.setLong("id", 1);
		Student stu = (Student) query.uniqueResult();
		System.out.println("Student Name=" + stu.getName() + ", Degre="
				+ stu.getDegree());

		tx.commit();
		session.close();
		factory.close();
	}
}

Program to update/delete data

package com.jwt.hibernate;

import java.util.List;

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

public class UpdateData {

	public static void main(String[] args) {

		Configuration cfg = new Configuration();
		cfg.configure("hibernate.cfg.xml");

		SessionFactory factory = cfg.buildSessionFactory();
		Session session = factory.openSession();
		Transaction tx = session.beginTransaction();

		// Update Employee
		Query query = session
				.createQuery("update Student set name= :name where id= :id");
		query.setParameter("name", "Amit Raj");
		query.setLong("id", 1);
		int result = query.executeUpdate();
		System.out.println("Student data Update Status=" + result);

		// Delete Employee, we need to take care of foreign key constraints too
		query = session.createQuery("delete from Student where id= :id");
		query.setLong("id", 3);
		result = query.executeUpdate();
		System.out.println("Student Data Delete Status=" + result);

		tx.commit();
		session.close();
		factory.close();
	}
}

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