part-2 click above links for more information on hibernate
or here
Hibernate3.2 with struts tutorial and assignment

Checking if objects are identical
Java defines two notations:
Object identity [==]
Equality of value [.equals()]
In SQL it is just checking if the two primary keys are the same.
Two or more objects can represent the same row of data.
Problem with SQL surrogate keys

>>what is Object Graph Navigation you will know in this presentation(power point slide ppt)

>>>>what is Object/relational Mapping (ORM)
ORM is the automated & transparent persistence of Java objects to tables in a RDBMS.

Metadata describes the mapping between the objects and the database.

ORM works by transforming data from one representation to another

Contains the following parts
API for CURD operations on objects

API for queries for classes & properties

Facility for mapping metadata

Technique for interaction with transactional objects

more info click below