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    <p>You've already had a few good answers here on how to do exactly as you ask..</p> <p>For reference let me just mention the recommended way to do this in Hibernate instead, which is to use a surrogate key as primary key, and to mark business keys as NaturalId's:</p> <blockquote> <p>Although we recommend the use of surrogate keys as primary keys, you should try to identify natural keys for all entities. A natural key is a property or combination of properties that is unique and non-null. It is also immutable. Map the properties of the natural key inside the element. Hibernate will generate the necessary unique key and nullability constraints and, as a result, your mapping will be more self-documenting.</p> <p>It is recommended that you implement equals() and hashCode() to compare the natural key properties of the entity.</p> </blockquote> <p>In code, using annotations, this would look something like this:</p> <pre><code>@Entity public class UserRole { @Id @GeneratedValue private long id; @NaturalId private User user; @NaturalId private Role role; } </code></pre> <p>Using this will save you a lot of headaches down the road, as you'll find out when you frequently have to reference / map the composed primary key.</p> <p>I found this out the hard way, and in the end just gave up fighting against Hibernate and instead decided to go with the flow. I fully understand that this might not be possible in your case, as you might be dealing with legacy software or dependencies, but I just wanted to mention it for future reference. (<em>if you can't use it maybe someone else can</em>!)</p>
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    1. COI don't know if Hibernate is going to give you anything over using JPA.
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      1. USJames McMahon
 

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