title: Assign rank number to rows with possible duplicates based on date
body: <p>I have a following table which stores bids</p>
  
  <pre><code>╔════════════╦═══════════╦══════════════════════╗
  ║ lot_id     ║  user_id  ║         date         ║
  ╠════════════╬═══════════╬══════════════════════╣
  ║ 123        ║ 9001      ║ 2017-08-09 14:33:55  ║
  ║ 123        ║ 9005      ║ 2017-08-09 14:33:55  ║
  ║ 123        ║ 9001      ║ 2017-08-09 14:44:55  ║
  ║ 124        ║ 8012      ║ 2017-08-09 14:55:55  ║
  ║ 124        ║ 9001      ║ 2017-08-09 14:55:55  ║
  ║ 124        ║ 9076      ║ 2017-08-09 14:66:55  ║
  ╚════════════╩═══════════╩══════════════════════╝
  </code></pre>
  
  <p>The idea is not to show user_id (due to security reasons), but instead showing user ordinal (sequential?) number which depends on the time he placed the bid.
  I need a query which will return me <code>first bidder</code>, <code>second bidder</code>, <code>N bidder</code> according to the <code>date</code>.</p>
  
  <p>This will be very inefficient doing it in PHP.</p>
  
  <p>P.S. It was kind of difficult to formulate the problem, so any suggestions in question title are welcome.</p>
  
  <p><strong>UPDATE</strong>
  Row number will not work. If the same user makes multiple bids the number should be the same. For example, if same user has made first bid an 10th bid it should display <code>first bidder</code></p>