title: Using an Alias in SQL Calculations
body: <p>Why won't this query work?</p>
  
  <pre><code>SELECT 10 AS my_num, my_num*5 AS another_number
  FROM table
  </code></pre>
  
  <p>In this example, I'm trying to use the my_num alias in other calculations.  This results in unknown column "my_num"</p>
  
  <p>This is a simplified version of what I am trying to do, but basically I would like to use an alias to make other calculations.  My calculations are much more complicated and thats why it would be nice to alias it since I repeat it several times different ways.</p>