title: in MYSQL select query reuse one of the selected column
body: <p>ySo here is my psuedo query.</p>
  
  <pre><code>Select `bigformula` as BIGQUERY, BIGQUERY*100 as percent from mytable group by employee_id
  </code></pre>
  
  <p>I am selecting and computing a bunch of things to derive <code>BIGQUERY</code>. Now i want to reuse <code>BIGQUERY</code> in the same select statment. How do i do that?</p>
  
  <p>Currently if i run the above column it gives:</p>
  
  <p><code>Error Code: 1054</code>
  Unknown column 'BIGQUERY' in 'field list'</p>
  
  <p>What other tricks can i use to achieve the same? Will there be a major performance drag with any of these trick. Please note that all the columns used in the query are indexed already and things are runing pretty quick so the indexes do work.</p>