title: Regex backslash issue in Redshift
body: <p>I can usually get by with Regex but this one's doing my head in and I will gratefully accept anyone's help.</p>
  <pre><code>select regexp_replace(upper('Abc\Zyxcz\'),'[^A-Z]+', '');
  </code></pre>
  <p>This returns <code>ABCZYXCZ\</code> although I'd expect it to remove all the backslashes.</p>
  <p>Anything I am missing? Thank you!</p>