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copied!<p>First of all, since the borrow table is a pure join table, you don't need to map it at all. All you need is a ManyToMany association using this borrow table as JoinTable.</p> <pre><code>@ManyToMany @JoinTable(name = "borrow", joinColumns = @JoinColumn(name = "USER_ID"), inverseJoinColumns = @JoinColumn(name = "BOOK_ID")) private List<Book> borrowedBooks; ... @ManyToMany(mappedBy = "borrowedBooks") private List<User> borrowingUsers; </code></pre> <p>If you really want to map the join table as an entity, then it should contain two ManyToOne associations (one for each foreign key). So the following is wrong:</p> <pre><code>@OneToMany(targetEntity=BorrowEntity.class, mappedBy="user") @JoinColumn(name="USER_ID", referencedColumnName="USER_ID") private List<BorrowEntity>borrowings; </code></pre> <p>Indeed, <code>mappedBy</code> means: this association is the inverse side of the bidirectional OneToMany/ManyToOne association, which is already mapped by the field <code>user</code> in the <code>BorrowEntity</code> entity. Please see the annotations on this field to know how to map the association.</p> <p>So the <code>@JoinColumn</code> doesn't make sense. It's in contradiction with <code>mappedBy</code>. You just need the following:</p> <pre><code>@OneToMany(mappedBy="user") private List<BorrowEntity>borrowings; </code></pre> <p>The targetEntity is also superfluous, since it's a <code>List<BorrowEntity></code>: JPA can infer the target entity from the generic type of the list.</p>

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