Hi ,
I am completly new to Hibernate, I was trying a sample example.

I have a table called Login on SQL server 2000.
When i try to save the records ,

//CODE

Login log=new Login();
log.setUsername("USER");
log.setPassword("PWD");
session.save(log);
tx.commit();

//END OF CODE


it throws me the below exception


net.sf.hibernate.exception.ConstraintViolationException: could not insert: [org.Login]
at net.sf.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:62)
at net.sf.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:29)
at net.sf.hibernate.persister.AbstractEntityPersister.convert(AbstractEntityPersister.java:1331)
at net.sf.hibernate.persister.EntityPersister.insert(EntityPersister.java:540)
at net.sf.hibernate.persister.EntityPersister.insert(EntityPersister.java:426)
at net.sf.hibernate.impl.ScheduledIdentityInsertion.execute(ScheduledIdentityInsertion.java:28)
at net.sf.hibernate.impl.SessionImpl.execute(SessionImpl.java:2449)
at net.sf.hibernate.impl.SessionImpl.doSave(SessionImpl.java:943)
at net.sf.hibernate.impl.SessionImpl.doSave(SessionImpl.java:868)
at net.sf.hibernate.impl.SessionImpl.saveWithGeneratedIdentifier(SessionImpl.java:786)
at net.sf.hibernate.impl.SessionImpl.save(SessionImpl.java:749)
at org.Test.main(Test.java:26)
Caused by: com.inet.tds.SQLException: Msg 515, Level 16, State 2, Line 1, Sqlstate 23000
[AEDXB-ASHKAR]Cannot insert the value NULL into column 'UserName', table 'Telecom_HelpDesk.dbo.Login'; column does not allow nulls. INSERT fails.
at com.inet.tds.q.a(Unknown Source)
at com.inet.tds.a.a(Unknown Source)
at com.inet.tds.k.a(Unknown Source)
at com.inet.tds.k.a(Unknown Source)
at com.inet.tds.k.b(Unknown Source)
at com.inet.tds.d.f(Unknown Source)
at com.inet.tds.d.execute(Unknown Source)
at net.sf.hibernate.persister.EntityPersister.insert(EntityPersister.java:502)
... 8 more

My Mapping XML IS

<hibernate-mapping package="org">

<class name="Login" table="Login">


<id name="username" column="UserName" type="string">
<generator class="native"/>
</id>

<property name="password" column="Password" type="string" />
</class>

</hibernate-mapping>

I can retrive records but cannot save
Please Help.

Thanks a million in Advance

Please follow the "Introduction to Hibernate" tutorial that comes with the Hibernate package, first chapter reference documentation. Use Hibernate 3.1 rc3.