title: update existing column value in JPA CriteriaUpdate
body: <p>i have an Entity User, and my DB value for user is:</p>
  
  <pre><code>name     totalScore
  --------------------
  ABC        25
  XYZ        30
  </code></pre>
  
  <p>Now i want to run the query</p>
  
  <pre><code>update user set totalScore=totalScore+ (2*totalScore);
  </code></pre>
  
  <p>How can we achive it through JPA 2.1 CriteriaUpdate ???</p>
  
  <pre><code>CriteriaBuilder criteriaBuilder = em().getCriteriaBuilder();
         //Updates the salary to 90,000 of all Employee's making more than 100,000.
          CriteriaUpdate update = criteriaBuilder.createCriteriaUpdate(User.class);
          Root user = update.from(User.class);
          Expression&lt;Long&gt; abc=user.get("totalScore");
  
          update.set("totalScore", ?? ); 
  // what expression is here to be used to replace old value with new 
          Query query = em().createQuery(update);
          int rowCount = query.executeUpdate();
  </code></pre>