title: How to reuse calculated columns avoiding duplicating the sql statement?
body: <p>I have a lots of calculated columns and they keep repeting themselves, one inside of the others, including nested cases statements. </p>
  
  <p>There is a really simplified version of something that i've searching a way to do.</p>
  
  <pre><code>SELECT 
      (1+2) AS A, 
      A + 3 AS B, 
      B * 7 AS C 
  FROM MYTABLE
  </code></pre>
  
  <p>Thanks in advance.</p>