title: Please explain about insertable=false and updatable=false in reference to the JPA @Column annotation
body: <p>If a field is annotated <code>insertable=false, updatable=false</code>, doesn't it mean that you cannot insert value nor change the existing value? Why would you want to do that?</p>
  
  <pre><code>@Entity
  public class Person {
  
      @Id
      @GeneratedValue(strategy = GenerationType.AUTO)
      private Long id;
  
      @OneToMany(mappedBy="person", cascade=CascadeType.ALL)
      private List&lt;Address&gt; addresses;
  }
  
  @Entity
  public class Address {
  
      @Id
      @GeneratedValue(strategy = GenerationType.AUTO)
      private Long id;
  
      @ManyToOne
      @JoinColumn(name="ADDRESS_FK")
      @Column(insertable=false, updatable=false)
      private Person person;
  }
  </code></pre>