title: Oracle get values from :new, :old dynamically by string key
body: <p>How to get a value from special <code>:new</code> or <code>:old</code> by "string key"?</p>
  
  <p>e.g. in PHP:</p>
  
  <pre><code>$key = 'bar';
  $foo[$key]; //get foo value
  </code></pre>
  
  <p>How to in Oracle?</p>
  
  <pre><code>:new.bar --get :new 'bar' value
  </code></pre>
  
  <p>and</p>
  
  <pre><code>key = 'bar';
  :new[key] --How to?
  </code></pre>
  
  <p>Is it possible?
  Thx!</p>