Not able to view the data persisted in the database.

[Kumar Raja]

Hello All,

I started working on a sample and simple hibernate application, that will persist "Person" objects and have few questions regarding this. I'm listing out the questions below:

Please find the following components

    
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>
        <property name="hibernate.connection.driver_class">org.hsqldb.jdbcDriver</property>
        <property name="hibernate.connection.url">jdbc:hsqldb:file:mydb</property>
        <property name="hibernate.connection.username">sa</property>
        <property name="hibernate.dialect">org.hibernate.dialect.HSQLDialect</property>
        <property name="show_sql">true</property>
        <property name="hibernate.connection.autocommit">true</property>
        <property name="hibernate.hbm2ddl.auto">update</property>
        <mapping  resource="com/hibertut/beans/Person.hbm.xml"/>
    </session-factory>
</hibernate-configuration>
         

    
Person.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated Mar 29, 2010 1:54:38 PM by Hibernate Tools 3.3.0.GA -->
<hibernate-mapping>
    <class name="com.hibertut.beans.Person" table="PERSON">
        <id name="id" type="java.lang.Long">
            <column name="ID" />
            <generator class="native" />
        </id>
        <property name="name" type="java.lang.String">
            <column name="NAME" />
        </property>
        <property name="ssn" type="java.lang.String">
            <column name="SSN" />
        </property>
    </class>
</hibernate-mapping>

    
Person.java

package com.hibertut.beans;

public class Person {
	private Long id=null;
	private String name=null;
	private String ssn=null;
	
	public Long getId(){
		return id;
	}
	private void setId(Long id){
		this.id=id;
	}
	
	public String getName(){
		return name;
	}
	
	public void setName(String name){
		this.name=name;
	}
	
	public String getSsn(){
		return ssn;
	}
	
	public void setSsn(String ssn){
		this.ssn=ssn;
	}
}

    
Client.java

public static void main(String[] args){
		Session session=null;
		Person s=null;
		
		SessionFactory sessionFactory=FactoryLocator.getInstance();
		session=sessionFactory.openSession();
		Transaction t=session.beginTransaction();
		t.begin();
		for(int i=0;i<5;i++){
			System.out.println("Inside loop");
			s=new Person();
			s.setName("Raja");
			s.setSsn("111-22-3333");
			session.save(s);
		}
		
		t.commit();
		
		Iterator i=session.createQuery("from Person").list().iterator();
		while(i.hasNext()){
			s=(Person)i.next();
			System.out.println("Id is "+s.getId());
			System.out.println("Name is "+s.getName());
			System.out.println("SSN is "+s.getSsn());
		}
		
	}

Q 1) When I run my client any time, I see only 5 objects being persisted? Why? Every time it runs, my assumption is,it should persist 5 objects and thus increasing the total count of persisted objects. I get the same thing, even I use a completely new session while retrieving "Person"s from the database.

Q 2) After every run, I'm trying to look into hsqldb (this is database used) but I do not see any table being created by name "PERSON". Am I looking at the right spot?

Q 3) If I remove "hibernate.hbm2ddl.auto" from configuration file, and run the client I get that table does not exist. I can understand this, because I did not find any table (see question 2). But why the table is not created.

Q 4) If I create a table PERSON explicitly and remove "hibernate.hbm2ddl.auto" from configuration file, and run the client, I get can not insert NULL into ID. Why is hibernate trying to insert null at first place for ID field.

Q 5) If I want to use a composite key, what do I need to modify?

Could you please look into this and advice ?

Thanks
Kumar

[Kumar Raja]

Could some one please look into my request and advice why the objects are not really persisted in the database, outside the program execution ?