title: How to enumerate returned rows in SQL?
body: <p>I was wondering if it would be possible to enumerate returned rows. Not according to any column content but just yielding a sequential integer index. E.g.</p>
  
  <pre><code>select ?, count(*) as usercount from users group by age
  </code></pre>
  
  <p>would return something along the lines:</p>
  
  <pre><code>1    12
  2    78
  3     4
  4    42
  </code></pre>
  
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