Hibernate

HQL Where Clause Example

Where Clause is used to limit the results returned from database. It can be used with aliases and if the aliases are not present in the Query, the properties can be referred by name. For example:
from UserDetails user where user.userId = 3

Look in 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 user WHERE user.userId = 2";
  Query query = session.createQuery(SQL_QUERY);
    
  for(Iterator it=query.iterate();it.hasNext();)
  {
   UserDetails user = (UserDetails)it.next();
   System.out.println("User Name: " + user.getUserName());
   System.out.println("User Id: " + user.getUserId());
  }
  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_ where userdetail0_.USER_ID=2
Hibernate: select userdetail0_.USER_ID as USER1_0_0_, userdetail0_.USER_NAME as USER2_0_0_ from USERS userdetail0_ where userdetail0_.USER_ID=?
User Name: Sweety Rajput
User Id: 2

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Dinesh Rajput

Dinesh Rajput is the chief editor of a website Dineshonjava, a technical blog dedicated to the Spring and Java technologies. It has a series of articles related to Java technologies. Dinesh has been a Spring enthusiast since 2008 and is a Pivotal Certified Spring Professional, an author of a book Spring 5 Design Pattern, and a blogger. He has more than 10 years of experience with different aspects of Spring and Java design and development. His core expertise lies in the latest version of Spring Framework, Spring Boot, Spring Security, creating REST APIs, Microservice Architecture, Reactive Pattern, Spring AOP, Design Patterns, Struts, Hibernate, Web Services, Spring Batch, Cassandra, MongoDB, and Web Application Design and Architecture. He is currently working as a technology manager at a leading product and web development company. He worked as a developer and tech lead at the Bennett, Coleman & Co. Ltd and was the first developer in his previous company, Paytm. Dinesh is passionate about the latest Java technologies and loves to write technical blogs related to it. He is a very active member of the Java and Spring community on different forums. When it comes to the Spring Framework and Java, Dinesh tops the list!

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