Restrictions query Hibernate

/**
 * This class represents a persistent class for Student.
 * @author w3spoint
 */
public class Student {
	//data members
	private int studentId;
	private String firstName;
	private String lastName;
	private String className;
	private String rollNo;
	private int age;
 
	//no-argument constructor
	public Student(){
 
	}
 
	//getter and setter methods
	public int getStudentId() {
		return studentId;
	}
	public void setStudentId(int studentId) {
		this.studentId = studentId;
	}
	public String getFirstName() {
		return firstName;
	}
	public void setFirstName(String firstName) {
		this.firstName = firstName;
	}
	public String getLastName() {
		return lastName;
	}
	public void setLastName(String lastName) {
		this.lastName = lastName;
	}
	public String getClassName() {
		return className;
	}
	public void setClassName(String className) {
		this.className = className;
	}
	public String getRollNo() {
		return rollNo;
	}
	public void setRollNo(String rollNo) {
		this.rollNo = rollNo;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
 
}

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-configuration SYSTEM
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
 
<hibernate-configuration>
 
    <session-factory>
        <property name="dialect">
           org.hibernate.dialect.OracleDialect
        </property>
        <property name="connection.url">
           jdbc:oracle:thin:@localhost:1521:XE
        </property>
        <property name="connection.username">
           system
        </property>
        <property name="connection.password">
           oracle
        </property>
        <property name="connection.driver_class">
           oracle.jdbc.driver.OracleDriver
        </property>
        <property name="hbm2ddl.auto">
           update
        </property>
        <property name="show_sql">
           true
        </property>
 
        <mapping resource="student.hbm.xml"/>
 
    </session-factory>
 
</hibernate-configuration>

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-mapping SYSTEM
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 
<hibernate-mapping>
 
 <class name="com.w3spoint.business.Student" table="Student">
  <id name="studentId" type="int" column="Student_Id">
	<generator class="native"></generator>
  </id>
 
  <property name="firstName" column="First_Name" type="string"/>
  <property name="lastName" column="Last_Name" type="string"/>
  <property name="className" column="Class" type="string"/>
  <property name="rollNo" column="RollNo" type="string"/>
  <property name="age" column="Age" type="int"/>
 
 </class>
 
</hibernate-mapping>

import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
 
/**
 * This is a utility class for getting the hibernate session object.
 * @author w3spoint
 */
public class HibernateUtil {
    private static final SessionFactory sessionFactory = 
                                           buildSessionFactory();
 
    private static SessionFactory buildSessionFactory() {
    	SessionFactory sessionFactory = null;
        try {
        	//Create the configuration object.
        	Configuration configuration = new Configuration(); 
        	//Initialize the configuration object 
                //with the configuration file data
        	configuration.configure("hibernate.cfg.xml");
        	// Get the SessionFactory object from configuration.
        	sessionFactory = configuration.buildSessionFactory();
        }
        catch (Exception e) {
           e.printStackTrace();
        }
        return sessionFactory;
    }
 
    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }
 
}

import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.criterion.Restrictions;
import com.w3spoint.persistence.HibernateUtil;
 
/**
 * This class is used for the hibernate operations.
 * @author w3spoint
 */
public class HibernateTest {
    public static void main(String args[]){
          //Create the student object.
         Student student = new Student();
 
        //Setting the object properties.
        student.setFirstName("Ashish");
        student.setLastName("Malik");
        student.setClassName("MCA final");
        student.setRollNo("MCA/07/21");
        student.setAge(27);
 
        //Get the session object.
        Session session = 
                HibernateUtil.getSessionFactory().openSession();
 
        //Start hibernate transaction.
        session.beginTransaction();
 
        //Persist the student object.
        session.save(student);
 
        //Commit hibernate transaction.
        session.getTransaction().commit();
 
        //select a student record using Criteria restriction query
        Criteria criteria = session.createCriteria(Student.class);
        criteria.add(Restrictions.eq("rollNo", "MCA/07/21"));
        Student stu = (Student) criteria.uniqueResult();
        System.out.println("First Name: " + stu.getFirstName()); 
        System.out.println("Last Name: " + stu.getLastName()); 
        System.out.println("Class: " + stu.getClassName()); 
        System.out.println("RollNo: " + stu.getRollNo()); 
        System.out.println("Age: " + stu.getAge());  
 
        //Close hibernate session.
        session.close();       		
   }
}

Hibernate: select hibernate_sequence.nextval from dual
Hibernate: insert into Student (First_Name, Last_Name, Class, 
RollNo, Age, Student_Id) values (?, ?, ?, ?, ?, ?)
Hibernate: select this_.Student_Id as Student1_0_0_, 
this_.First_Name as First2_0_0_, this_.Last_Name as
Last3_0_0_, this_.Class as Class0_0_, this_.RollNo as
RollNo0_0_, this_.Age as Age0_0_ from 
Student this_ where this_.RollNo=?
First Name: Ashish
Last Name: Malik
Class: MCA final
RollNo: MCA/07/21
Age: 27