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POIn a bidirectional JPA OneToMany/ManyToOne association, what is meant by "the inverse side of the association"?
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  1. POIn a bidirectional JPA OneToMany/ManyToOne association, what is meant by "the inverse side of the association"?
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    copied!<p>In these examples on <a href="http://www.oracle.com/technetwork/middleware/ias/toplink-jpa-annotations-096251.html#OneToMany" rel="noreferrer">TopLink JPA Annotation Reference</a>:</p> <p><strong>Example 1-59 @OneToMany - Customer Class With Generics</strong></p> <pre><code>@Entity public class Customer implements Serializable { ... @OneToMany(cascade=ALL, mappedBy="customer") public Set&lt;Order&gt; getOrders() { return orders; } ... } </code></pre> <p><strong>Example 1-60 @ManyToOne - Order Class With Generics</strong></p> <pre><code>@Entity public class Order implements Serializable { ... @ManyToOne @JoinColumn(name="CUST_ID", nullable=false) public Customer getCustomer() { return customer; } ... } </code></pre> <p>It seems to me that the <code>Customer</code> entity is the owner of the association. However, in the explanation for the <code>mappedBy</code> attribute in the same document, it is written that:</p> <blockquote> <p>if the relationship is bidirectional, then set the mappedBy element on the inverse (non-owning) side of the association to the name of the field or property that owns the relationship as Example 1-60 shows.</p> </blockquote> <p>However, if I am not wrong, it looks like in the example, the <code>mappedBy</code> is actually specified on the owning side of the association, rather than the non-owning side.</p> <p>So my question is basically:</p> <ol> <li><p>In a bidirectional (one-to-many/many-to-one) association, which of the entities is the owner? How can we designate the One side as the owner? How can we designate the Many side as the owner?</p></li> <li><p>What is meant by "the inverse side of the association"? How can we designate the One side as the inverse? How can we designate the Many side as the inverse?</p></li> </ol>
 

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