Hi,
I have DB structure as below:

Table Person:
ID : Primary Key
Age

Table Name:
ID : Primary Key : Foreign Key Person(ID)
First_Name
Last_Name

I have my POJOs as below:

class Env
{
private int id;
private int age;
private Name name;
}

class Name
{
private int id;
private String firstName;
private String lastName;
}

I'm new to Hibernate. I have an urgent requirement to implement a similar thing as above. I read many articles on net, but could not get a solution to above. Some of the places i found NAME_ID as a primary key to Name table and a reference is stored in Person table. But my requirement is as above.

Please help me with getting correct mapping.

As I understand, you would like to use the same value for primary key in both tables. This is a Shared Primary key scenario. It can be implemented with the following:

1. Add an attribute of type Env to Name class, this will establish a bi-directional association.
2. Add <one-to-one> tag with the appropriate attributes in the .hbm.xml files for both classes.
3. In the .hbm.xml file for Name class, you also need to add the following xml elements
<id name="id" column="ID">
<generator class="foreign">
<param name="property">env</param>
</generator>
</id>

env in step 3 refers to the reference of Env class in Name that you need to add.

Hi Jagan,
Thanks for the quick response...

I still have few queries -
First thing is i want my association to be uni-directional, from Person to Name. So is it still needed to have a reference to Person in Name class? (class "Env" was a typo...please consider it as "Person")

Also i have mapped the entities as below:

<class name="Person" table="PERSON" >
<id column="ID" name="id" />
<property column="AGE" name="age" />
<one-to-one name="name" class="Name"/>
</class>

<class name="Name" table="NAME" >
<id name="id" column="ID">
<generator class="foreign">
<param name="property">person</param>
</generator>
</id>
<property column="FIRST_NAME" name="firstName" />
<property column="LAST_NAME" name="lastName" />
<one-to-one name="person" class="Person" constrained="true" />
</class>

Please correct me if i have done anything wrong above.

Also, how would i need to query to get a Person Object having a reference to a Name object based on ID?

Thanks in advance :)
-Pranit

Pranit,

I believe you need to have Bi-directional association here to have the shared primary key. In Hibernate, we cant seem to do this with a Uni-directional association.

Using JPA with annotations, this seems to be possible with Uni-directional assoc. But again, we need to do a bit of jugglary.

Regards.

see pranit...if it is bi-directional then at one side you need to write a one-to-one and otherside many-to-one...vice versa....


if it is unidirectional then write a many-to-one tag on oneside..............thats enough..............on the otherside u need not write any relation..or reference belong to opposite mapping class.....

in hibernate we can use many to one tag for one to one relation--unidirectional...........