Question

I have the following Hibernate Mapping, which has to be mapped using the Table per Concrete Class Hierarchy:

<hibernate-mapping package='dao'>     <meta attribute='class-description'></meta>     <class name='PropertyDAO'>         <id name='id' column='id_property'>             <generator class='assigned'/>         </id>         <property name='address' column='address' type='string'/>         <union-subclass name='HouseDAO' table='house'>             <property name='noOfRooms' column='noOfRooms'/>             <property name='totalArea' column='totalArea'/>             <property name='price' column='price'/>         </union-subclass>         <union-subclass name='LandDAO' table='land'>             <property name='area' column='area'/>             <property name='unitPrice' column='unitPrice'/>         </union-subclass>     </class> </hibernate-mapping> 

Which means in the database i have only 2 tables :

• house (id_property(PK), address, noOfRooms, totalArea, price)
• land (id_property(PK), address, area, unitPrice)

As far as I understood, in this case the ids need to be generated explicitly before calling .save(), so my question is: How can I create a strategy for the automatically generation of the ids, so that the ids from the concrete class form a continuous domain when joined.

Answer 1

The solution is to create another table that stores the next id; this value should be modified each time a user wants to insert a new entity. In this way, the domain is continuous