title: in sql, how to make a rank column based on the value of another column?
body: <p>say I wish to create a table like following:</p>
  
  <pre><code>user   score   rank
  a      100     2   
  b      200     1
  c      50      3
  d      50      3
  </code></pre>
  
  <p>How exactly do I create a <code>rank</code> column in which it updates with the new entry of record with <code>score</code>?</p>