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hibernate criteria Distinct
Posted on: April 7, 2011 at 12:00 AM
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In This example search the result according to Criteria Restriction and like condition. The DISTINCT_ROOT_ENTITY field is ensures that each row of results is a distinct instance of the root entity.

hibernate criteria Distinct

In this Tutorial, We will discuss about hibernate criteria query, In this example we create a criteria instance and implement the factory methods for obtaining certain built-in Criterion types method. In This example search the result according to Criteria Restriction  and like condition. The DISTINCT_ROOT_ENTITY field is ensures that each row of results is a distinct instance of the root entity.

Here is the simple Example code files.

CriteriaDistincExample.java

package roseindia;

import java.util.Iterator;
import java.util.List;
import org.hibernate.Criteria;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.criterion.Restrictions;
import roseindia.bean.User;
import roseindia.util.HibernateUtil;

public class CriteriaDistincExample {

	public static void main(String[] args) {

		Session session = HibernateUtil.getSessionFactory().openSession();

		User user = null;

		try {
			// Creating a Criteria instance
		Criteria crit = session.createCriteria(User.class);
		crit.add(Restrictions.like("UserName", "User%"));
		crit.add(Restrictions.gt("expInMonth", 50));
		crit.setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY);
		List list = crit.list();
		Iterator itr = list.iterator();
		while (itr.hasNext()) {
			user = (User) itr.next();
			System.out.println("UserId: " + user.getUserId());
			System.out.printf("\t");
			System.out.println("UserName: " + user.getUserName());
			System.out.printf("\t");
			System.out.println("UserAddr: " + user.getUserAddr());
			System.out.printf("\t");
			System.out.println("ExpInMonth: " + user.getExpInMonth());

			}

		} catch (HibernateException e) {

			e.printStackTrace();
		} finally {
			session.close();
		}

	}

}

The bean class is as follows.

package roseindia.bean;

import java.util.Date;

public class User implements java.io.Serializable {

	private static final long serialVersionUID = 1L;

	private long Id = 0;
	private int UserId = 0;
	private String UserName = null;
	private String UserAddr = null;
	private String UserPhone = null;
	private String UserEmail = null;
	private Date UserDOB = null;
	private int expInMonth = 0;
	private double UserIncome = 0.0;

	public User() {
	}

	public User(int UserId, String UserName, String UserAddr, String UserPhone,
		String UserEmail, Date UserDOB, int expInMonth, double UserIncome) {
		this.UserId = UserId;
		this.UserName = UserName;
		this.UserAddr = UserAddr;
		this.UserPhone = UserPhone;
		this.UserEmail = UserEmail;
		this.UserDOB = UserDOB;
		this.expInMonth = expInMonth;
		this.UserIncome = UserIncome;
	}

	public long getId() {
		return Id;
	}

	public void setId(long id) {
		Id = id;
	}

	public int getUserId() {
		return UserId;
	}

	public void setUserId(int userId) {
		UserId = userId;
	}

	public String getUserName() {
		return UserName;
	}

	public void setUserName(String userName) {
		UserName = userName;
	}

	public String getUserAddr() {
		return UserAddr;
	}

	public void setUserAddr(String userAddr) {
		UserAddr = userAddr;
	}

	public String getUserPhone() {
		return UserPhone;
	}

	public void setUserPhone(String userPhone) {
		UserPhone = userPhone;
	}

	public String getUserEmail() {
		return UserEmail;
	}

	public void setUserEmail(String userEmail) {
		UserEmail = userEmail;
	}

	public Date getUserDOB() {
		return UserDOB;
	}

	public void setUserDOB(Date userDOB) {
		UserDOB = userDOB;
	}

	public int getExpInMonth() {
		return expInMonth;
	}

	public void setExpInMonth(int expInMonth) {
		this.expInMonth = expInMonth;
	}

	public double getUserIncome() {
		return UserIncome;
	}

	public void setUserIncome(double userIncome) {
		UserIncome = userIncome;
	}

	@Override
	public String toString() {
		return "User [UserAddr=" + UserAddr + ", UserDOB=" + UserDOB
		+ ", UserEmail=" + UserEmail + ", UserId=" + UserId
		+ ", UserName=" + UserName + ", UserPhone=" + UserPhone
		+ ", UserSalary=" + UserIncome + ", expInMonth=" + expInMonth+ "]";
	}

}

We use the following code to insert the values in the database table using mapping file.

DataInsert.java

package roseindia;

import java.util.Date;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.Transaction;
import roseindia.bean.User;
import roseindia.util.HibernateUtil;

public class DataInsert {

	public static void main(String[] args) {

		Session session = HibernateUtil.getSessionFactory().openSession();
		Transaction transaction = null;
		User user = null;

		try {
			transaction = session.beginTransaction();
			for (int i = 0; i < 10; i++) {
				user = new User(1 * i, "User " + i, "NEW DELHI" + i,
				"999999458" + i, "User@gmail.com" + i, new Date(),
						12 * i, 25000.00 * i);
				session.save(user);
			}
			transaction.commit();
		} catch (HibernateException e) {
			transaction.rollback();
			e.printStackTrace();
		} finally {
			session.close();
		}
	}
}

The database table mapping is in the file User.hbm.xml and hibernate configuration file is hibernate.cfg.xml.

hibernate.cfg.xml

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- Database connection settings -->
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://localhost:3306/test</property>
<property name="connection.username">root</property>
<property name="connection.password"></property>
<!-- JDBC connection pool (use the built-in) -->
<property name="connection.pool_size">10</property>
<!-- SQL dialect -->
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<!-- Enable Hibernate's automatic session context management -->
<property name="current_session_context_class">thread</property>
<!-- Disable the second-level cache -->
<property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
<!-- Echo all executed SQL to stdout -->
<property name="show_sql">true</property>
<!-- Drop and re-create the database schema on startup -->
<property name="hbm2ddl.auto">update</property>
<mapping resource="roseindia/bean/User.hbm.xml" />

</session-factory>

</hibernate-configuration>

The User.hbm.xml file is as follows-

 <?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="roseindia.bean.User" table="UserData">
<id name="Id" type="long" column="ID">
<generator class="native" />
</id>
<property name="UserId" type="int" length="100" not-null="false"
column="USER_ID" />
<property name="UserName" type="java.lang.String" length="100"
not-null="false" column="USER_NAME" />
<property name="UserAddr" type="java.lang.String" length="100"
not-null="false" column="USER_ADDR" />
<property name="UserPhone" type="java.lang.String" length="100"
not-null="false" column="USER_PHONE" />
<property name="UserEmail" type="java.lang.String" length="100"
not-null="false" column="USER_EMAIL" />
<property name="UserDOB" type="java.util.Date" not-null="false"
column="USER_DOB" />
<property name="expInMonth" type="int" not-null="false"
column="EXP_IN_MONTH" />
<property name="UserIncome" type="double" not-null="false"
column="USER_INCOME" />
</class>
</hibernate-mapping>

The HibernateUtil.java is as follows, is used to get the SessionFactory object to open session.

package roseindia.util;

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

public class HibernateUtil {
	private static final SessionFactory sessionFactory;
	static {
		try {
			sessionFactory = new Configuration().configure()
					.buildSessionFactory();
		} catch (Throwable ex) {
		System.err.println("Initial SessionFactory creation failed." + ex);
			throw new ExceptionInInitializerError(ex);
		}
	}

	public static SessionFactory getSessionFactory() {
		return sessionFactory;
	}
}

This example give the output the values from the table according to the criteria defined.

The structure of the database table is as follows:

The resultant query generated by hibernate is as follows which produces the output as follows

Hibernate: select this_.ID as ID0_0_, this_.USER_ID as USER2_0_0_, this_.USER_NAME 
as USER3_0_0_, this_.USER_ADDR as USER4_0_0_, this_.USER_PHONE as 
USER5_0_0_, this_.USER_EMAIL as USER6_0_0_, this_.USER_DOB as USER7_0_0_, 
this_.EXP_IN_MONTH as EXP8_0_0_, this_.USER_INCOME as USER9_0_0_ from 
UserData this_ where this_.USER_NAME like ? and this_.EXP_IN_MONTH>?

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