title: Sql query to get user id having latest date time
body: <p>I have one table having <br></p>
  
  <pre><code>**user_id** | **date**
  1           | 2012-10-18 09:34:4
  3           | 2012-10-18 09:34:54
  5           | 2012-10-17 09:14:54
  6           | 2012-10-17 09:13:24
  4           | 2012-10-16 08:34:54
  9           | 2012-10-16 08:34:54
  </code></pre>
  
  <p>What I want is user_id with latest date-time i.e</p>
  
  <pre><code>**user_id** | **date**
  3           | 2012-10-18 09:34:54
  5           | 2012-10-17 09:14:54
  4           | 2012-10-16 08:34:54
  </code></pre>