title: Identifying trend with SQL query
body: <p>I have a table (let's call it Data) with a set of object IDs, numeric values and dates. I would like to identify the objects whose values had a positive trend over the last X minutes (say, an hour).</p>
  
  <p>Example data:</p>
  
  <pre><code>entity_id | value | date
  
  1234      | 15    | 2014-01-02 11:30:00
  
  5689      | 21    | 2014-01-02 11:31:00
  
  1234      | 16    | 2014-01-02 11:31:00
  </code></pre>
  
  <p>I tried looking at similar questions, but didnt find anything that helps unfortunately...</p>