title: How to make to_number ignore non-numerical values
body: <p>Column xy of type 'nvarchar2(40)' in table ABC.</p>
  
  <p>Column consists mainly of numerical Strings</p>
  
  <p>how can I make a</p>
  
  <pre><code>select to_number(trim(xy)) from ABC
  </code></pre>
  
  <p>query, that ignores non-numerical strings?</p>