HQL from clause Example

In this example you will learn how to use the HQL from clause. The from clause is the simplest possible Hibernate Query. Example of from clause is..

See the Example.
UserDetails.java
package com.sdnext.hibernate.tutorial.dto;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="USERS")
public class UserDetails 
{
 @Id
 @Column(name="USER_ID")
 @GeneratedValue(strategy=GenerationType.AUTO)
 private int userId;
 
 @Column(name="USER_NAME")
 private String userName;
 
 public int getUserId() {
  return userId;
 }
 public void setUserId(int userId) {
  this.userId = userId;
 }
 public String getUserName() {
  return userName;
 }
 public void setUserName(String userName) {
  this.userName = userName;
 }
}
hibernate.cfg.xml
<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/hibernateDB</property> 
   <property name="connection.username">root</property> 
   <property name="connection.password">root</property> 

  <!-- JDBC connection pool (use the built-in) -->
   <property name="connection.pool_size">1</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 class="com.sdnext.hibernate.tutorial.dto.UserDetails">
   
  </mapping></session-factory> 
 </hibernate-configuration>
HibernateTestDemo.java
package com.sdnext.hibernate.tutorial;

import java.util.Iterator;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;

import com.sdnext.hibernate.tutorial.dto.UserDetails;

public class HibernateTestDemo {
 /**
  * @param args
  */
 public static void main(String[] args) 
 {
  SessionFactory sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();
  Session session = sessionFactory.openSession();
  session.beginTransaction();
  
  String SQL_QUERY = "FROM UserDetails";
  Query query = session.createQuery(SQL_QUERY);
    
  for(Iterator it=query.iterate();it.hasNext();)
  {
   UserDetails user = (UserDetails)it.next();
   System.out.println("ID: " + user.getUserId());
   System.out.println("User Name: " + user.getUserName());
  }
  session.getTransaction().commit();
  session.close();
 }
}
Output:
log4j:WARN No appenders could be found for logger (org.hibernate.cfg.annotations.Version).
log4j:WARN Please initialize the log4j system properly.
Hibernate: select userdetail0_.USER_ID as col_0_0_ from USERS userdetail0_
Hibernate: select userdetail0_.USER_ID as USER1_0_0_, userdetail0_.USER_NAME as USER2_0_0_ from USERS userdetail0_ where userdetail0_.USER_ID=?
ID: 1
User Name: Dinesh Rajput
Hibernate: select userdetail0_.USER_ID as USER1_0_0_, userdetail0_.USER_NAME as USER2_0_0_ from USERS userdetail0_ where userdetail0_.USER_ID=?
ID: 2
User Name: Sweety Rajput
Hibernate: select userdetail0_.USER_ID as USER1_0_0_, userdetail0_.USER_NAME as USER2_0_0_ from USERS userdetail0_ where userdetail0_.USER_ID=?
ID: 3
User Name: Dev Rajput
Hibernate: select userdetail0_.USER_ID as USER1_0_0_, userdetail0_.USER_NAME as USER2_0_0_ from USERS userdetail0_ where userdetail0_.USER_ID=?
ID: 4
User Name: Anamika Rajput




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