Hi,

I implement the inheritance with table per-subclass strategy,
but i have some problems:

I have 1 mapping file and 3 POJO's that represent this 3
tables:

===============================================
PERSON
--------
ID (Primary Key)
NAME
EMAIL

CLIENT
--------
ID (Primary Key and Foreign Key to table Person)
CREDITCARD

EMPLOYEE
---------
ID (Primary Key and Foreign Key to table Person)
SALARY
===============================================

The classes Client and Employee extends Person.

I have the situation that one client can be a employee too.
If I include a new Client, a new id is generated.
If I get this Id and create a new Employee with this, when
I save, a new Id is generated and a new Person is created.
My goal was that only a new Employee was inserted, the person
was exist in the Person table.
How I can do this??

My mapping-files:

===============================================
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd" >

<hibernate-mapping>

<class name="com.transportes.Person"
table="person">

<id name="id"
type="java.lang.Long"
column="id">

<generator class="sequence">
<param name="sequence">person_id_seq</param>
</generator>
</id>

<property name="name"
type="java.lang.String"
column="name"
not-null="true"
length="60"/>

<property name="email"
type="java.lang.String"
column="email"
not-null="false"
length="60"/>

<joined-subclass
name="com.transportes.Client"
table="client">

<key column="id"/>

<property
name="creditCard"
type="java.lang.String"
column="creditCard"
not-null="false"
length="10"/>
</joined-subclass>

<joined-subclass
name="com.transportes.Employee"
table="employee">

<key column="id"/>

<property
name="salary"
type="java.lang.Long"
column="salary"
not-null="false"/>
</joined-subclass>

<joined-subclass
name="com.transportes.vo.ProprietarioVO"
table="proprietario">

<key column="id"/>

<property
name="nascimento"
type="java.util.Date"
column="nascimento"
not-null="false"/>
</joined-subclass>

</class>
</hibernate-mapping>

===============================================

Thanks

When you create an instance of "client", you get two new rows: one in the table
"client", a second in the table "person".
Now you want to create an "employee" that uses the row in table "person" as well as
the "client" does, right?

This is not possible. In fact it's wrong. Logically the client-object consists of two rows.
An employee consist of two rows, one in table "employee", a second in table "person".

My suggestion: Do not use inheritance. Use Delegation. Have three classes
"person", "client" and "employee" and a one-to-one association between client and
person on the one hand and a one-to-one association between employee and
person.
That way a client "is a" person and an employee "is a" person. Both point to the same
person, and you have just one row in table "person".

Hope this helps.
Erik