title: How to calculate the sum of two different fields in a SoQL query
body: <p>I'm making a query in soql to calculate the mean value of two numeric fields H01 and H02 in a json file, whose values are 6 and 4, respectively. This query gets a single record. The query is like this:</p>
  
  <pre><code>query="SELECT H01,H02, $((H01 + H02))/2 AS AVERAGE WHERE pollutant = 'H6' AND DATA = '2020-05-08T00:00:00.000' AND location = 'London'"
  </code></pre>
  
  <p>However, when executing this query, the AVERAGE value gives 0, when in fact it is 10.</p>
  
  <p>What am I doing wrong?</p>