Hi,

I am new to hibernate. I am having parent table related with multiple child tables.

How can i write hbm.xml files for parent and child tables.

Help me..


Thanks
Ahamad

Have a look at Chapters 6 and 7 of the documentation:

http://www.hibernate.org/hib_docs/v3/reference/en/html/

You can have more the one kind of inheritance.

If you have one table for each class, you will use inheritance of table for subclass. You should map only the superclass and the subclasses are mapped in the superclass map file.

<hibernate-mapping>
<class name="SuperClass" table="SuperClass">
<id name="ID_SUPERCLASS" type="Int">
<generator class="XXX"/>
</id>

<property name="XXX" type="int"/>

<joined-subclass name="SubClass1" table="SubClass1">
<key column="ID_SUBCLASS1"/>
<property name="XXX" type="int"/>
</joined-subclass>

<joined-subclass name="SubClass2" table="SubClass2">
<key column="ID_SUBCLASS2"/>
<property name="XXX" type="int"/>
</joined-subclass>
</class>
</hibernate-mapping>

If you have just one table for both superclass and subclasses, you will use inheritance of table for class hierarchy. In this case, your table need to have a column to indentify the subclasses called discriminator column.

<hibernate-mapping>
<class name="SuperClass" table="SuperClass">
<id name="ID_SUPERCLASS" type="Int">
<generator class="XXX"/>
</id>
<discriminator column="Class_Type" type="String"/>

<!--properties of superclass-->
<property name="XXX" type="Int"/>

<!--subclass map-->
<subclass name="SubClass1"
discriminator-value="SubClass1_discriminator">
<!--subclass1 properties-->
<property name="XXX" type="Int"/>
<property name="XXX" type="Int"/>
</subclass>
<subclass name="SubClass2"
discriminator-value="SubClass2_discriminator">
<!--subclass2 properties-->
<property name="XXX" type="Int"/>
<property name="XXX" type="Int"/>
</subclass>
</class>
</hibernate-mapping>