title: How to do a regexp_replace for a single hiphen character?
body: <p>I would like to replace hiphens in a column with 2 hiphens. I want to do this only if hiphen occurs by itself. For example</p>
  
  <ol>
  <li><code>'-'</code> should become <code>'--'</code></li>
  <li><code>'a-b'</code> should remain as <code>'a-b'</code></li>
  <li><code>'a - b'</code> should become <code>a -- b</code></li>
  <li><code>'a -'</code> should become <code>a --</code></li>
  <li><code>'- b'</code> should become <code>-- b</code></li>
  </ol>
  
  <p>What I have tried so far is <code>select regexp_replace(column, '[[:&lt;:]]\-[[:&gt;:]]', '--', 'gi')</code>. This is not working since the <code>'a-b'</code> becomes <code>'a--b'</code></p>
  
  <p>How should I proceed?</p>