title: Postgres convert integer into time
body: <p>I need to convert the following (hh)integer column into a time column. Expected results below:</p>
  
  <pre><code>hh     time
  1      00:00
  2      00:30
  3      01:00
  4      01:30
  ...
  48     23:30
  </code></pre>
  
  <p>Can you help?</p>