title: How to get average value according their value in mysql
body: <p>I'm trying to get result of data and their hole average, according to their value, example : </p>
  
  <pre><code>select sum(rank) as value,area from temp GROUP BY area
  </code></pre>
  
  <pre>
  value | Area
  ------+-------
  15    | East
  54    | North
  49    | South
  35    | West
  </pre>
  
  <p>but I want to their total avg like </p>
  
  <pre>
  value | Area  | Average
  ------+-------+---------
  49    | East  | 40
  15    | North | 40
  56    | South | 40
  40    | West  | 40
  </pre>
  
  <p>How I can get these ? plz help</p>