Question

Is it possible to do Table Inheritance in Java DB? We have a complex code model that uses inheritance and would also benefit from DB inheritance.

Is it possible? It doesn’t seem possible from a quick google or a poke around in netbeans.

Cheers

Answer 1

First, your question is fairly vague in the details. The more specific you are the better the community can support you. So I’m going to guess what support you are looking for and hope it helps.

If you’re using something like JPA/Hibernate, you can create classes with the annotation @MappedSuperClass. When the classes are scanned, the relationship between a ‘parent’ table and a child table will be realized. As a quick example:

@MappedSuperClass
public class Foo {
    private Long id;
    // ... getters and setters
}

@Table("BAR")
@AttributeOverride(name="id" column=@Column(name = "BAR_ID"))
public class Bar extends Foo {
    // ... map your table
}

If you’ll notice, the Foo class does not have to represent a table. It can just provide some of the common fields that span across a number of tables (typical fields like modified_by, modified_date, etc.). If Bar has an id like BAR_ID, you can then override the parent with an @AttributeOverride annotation.

While I did everything with annotations, I’m sure you can look into doing this with XML as well.