Java Reference
In-Depth Information
The Catalog entity has a many-to-many relationship with the Edition entity. We
shall make the Catalog entity the owning-side of the relationship. The join table
is defined on the owning side and cascade operations may be initiated only from
the owning side. Specify the @ManyToMany annotation in the Catalog entity with
cascade element set to ALL , as we want to cascade all changes to the associated
Edition entities when a Catalog entity is deleted. Setting cascading to ALL does
degrade performance slightly, as extra queries are required to be created, but
cascading propagates modifications to the associated entities.
name="catalogId", referencedColumnName="ID"),
@JoinColumn(name="editionId", referencedColumnName="ID"))
The join table, CATALOGEDITIONS , is generated by the EJB container when the EJB
is deployed to the server; therefore, we don't need to generate the join table. The
join column catalogId references the primary key id of the CATALOG table, and the
inverse join column editionId references the primary key id of the EDITION table.
The cascade element is set to ALL , which implies that all operations are cascaded.
The Catalog entity bean class is listed next:
package model;
import javax.persistence.*;
import java.util.*;
@NamedQuery(name="findCatalogAll", query="SELECT c FROM Catalog c"),
query="SELECT c FROM Catalog c
WHERE c.journal = :journal")
public class Catalog implements Serializable {
static final long serialVersionUID = 1;
private int id;
private String journal;
private List<Edition> editions;
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