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Hibernate Named Query

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Named Query is very useful concept in hibernate. It lets you separate queries from coding section of the application to the mapping xml file(.hbm files).

Hibernate Named Query

     

Named Query is very useful concept in hibernate. It lets you separate queries from coding section of the application to the mapping xml file(.hbm files). The query is given unique name for the entire application. The application can use the query by using the name of the query. This way the application is able to use the same query multiple times without writing the same query multiple times.

Defining the query in hbm file: (Put query inside ‚??hibernate-mapping‚?? element, but don't put it before the ‚??class‚?? element)

<?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="net.roseindia.hibernate.model.Contact" table="contact">

<id name="id" type="long" column="ID" >

<generator class="increment"/>

</id>

<property name="firstName">

<column name="first_name" />

</property>

<property name="lastName">

<column name="last_name"/>

</property>

</class>

<query name="findContactByFirstName">

<![CDATA[from Contact c where c.firstName = :firstName]]>

</query>

</hibernate-mapping>

 

Calling Named Query in the coding section

You can call the named query with getNamedQuery method which takes the name of the query as parameter.

package net.roseindia.example;

import java.util.List;

import net.roseindia.hibernate.model.Contact;

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

public class NamedQueryExample {
public static void main(String[] args) {
Session session = null;

try{
SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
session =sessionFactory.openSession();

Query query = session.getNamedQuery("findContactByFirstName").setString("firstName", "Ravi");
List results = query.list();
System.out.println("No of Results: " + results.size());

}catch(Exception e){
System.out.println(e.getMessage());
}finally{
session.flush();
session.close();

}

}
}

The Structure of the table is as follows:

CREATE TABLE `contact` (
`ID` bigint(20) NOT NULL,
`first_name` varchar(255) default NULL,
`last_name` varchar(255) default NULL,
PRIMARY KEY (`ID`)
)

Download the hibernate application for eclipse.

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Posted on: January 20, 2011

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