title: Define a variable in Entity class which is not a column
body: <p>In my WAS application, I have a requirement to define a variable(String) in an Entity class that maps to a table.
  So the fields that are related to the table have annotation as @Column(name="column_name")
  I have a requirement to add a new field/variable to this Entity class that is not a column in table. If I declare it as a normal field, JPA converts this field also in the SQLs. This is causing SQL -206 error(as expected).</p>
  
  <p>How to do I declare this field? Is there an annotation that I can use to say its a custom variable and not related to any of the columns in the table defined by this Entity?</p>
  
  <p>example:</p>
  
  <pre><code>@Entity
  @Table(name = "TABLE_1")
  @NamedQueries(
   {
  @NamedQuery(name = "abc:findTableContent", query = "SELECT u FROM TABLE_1 u WHERE u.Id = :iD"),
   })
  public class TableEntity1 implements Serializable
  {
      @Id
      @Column(name = "TABLE1_ID")
      private Long iD;
  
      @Column(name = "DESC")
      private String desc;
  
  
      private String error;    
  
  
  }
  </code></pre>
  
  <p>So if I run the namedquery, it gets executed as "SELECT t0.iD, t0.desc, t0.error FROM TABLE_1 u WHERE u.iD=?"</p>
  
  <p>How do I solve this? Thanks for your help!</p>