title: Query to split even and odd numbers, with GROUP_CONCAT
body: <p>I have a query that finds housenumbers per street in a specific postcode with four numbers:</p>
  
  <pre><code>SELECT *,
      GROUP_CONCAT(DISTINCT CAST(housenumber AS int) ORDER BY housenumber ASC) AS housenumbers
  FROM streets
  WHERE postcode LIKE '3031%'
  GROUP BY street
  ORDER BY lat,lon
  </code></pre>
  
  <p>This is the result of the groupcatted housenumbers.</p>
  
  <pre><code>491,492,493,500,501,502,503,504,505,506,507,508,50
  </code></pre>
  
  <p>I would like to split the result, over two columns, in evenhousenumber and oddhousenumbers.
  I tried <code>MOD</code> and <code>%2</code>, but both require a <code>WHERE</code> and it's not possible to use the <code>WHERE</code> in the groupcat function, I noticed.</p>
  
  <p>How can I split the result, over even and odd numbers?</p>