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Oracle® Containers for J2EE Enterprise JavaBeans Developer's Guide 10g Release 3 (10.1.3) B14428-01 |
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# Configuring a One-to-Many Mapping

Use a 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 7-18 shows how to use the `@OneToMany` annotation to specify a one-to-many mapping for field `managedEmployees`.

Example 7-18 @OneToMany

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