Configuring an One-to-Many Mapping

Use an one-to-many mapping to represent the relationship between a single source object and a collection of target objects. This relationship is a good example of something that is simple to implement in Java using a Vector (or other collection types) of target objects, but difficult to implement using relational databases.

You define a one-to-many mapping at one of the property (getter or setter method) or field level of your entity.

For more information, see "Understanding One-to-Many Mapping" in the Oracle TopLink Developer's Guide.

Note:

For an EJB 3.0 basic mapping code example, see: http://www.oracle.com/technology/tech/java/oc4j/ejb3/howtos-ejb3/howtoejb30mappingannotations/doc/how-to-ejb30-mapping-annotations.html#onetomany.

Using Annotations

Example 7-22 shows how to use the @OneToMany annotation to specify an one-to-many mapping for field managedEmployees.

Example 7-22 @OneToMany

@OneToMany(cascade=PERSIST)
@JoinColumn(name="MANAGER_ID", referencedColumnName="EMP_ID")
public Collection getManagedEmployees() {
    return managedEmployees;
}