title: Laravel - query builder to select multiple rows with unique column value (which has max value from another column)
body: <p>I have a table like this</p>
  
  <pre><code>data | usage_date | usage_hour
  x    | 03/03/2016 | 05:30:30
  y    | 03/02/2016 | 11:30:30
  z    | 03/03/2016 | 07:30:30
  p    | 03/02/2016 | 05:30:30
  </code></pre>
  
  <p>When I run Laravel query I would like see following rows being selected</p>
  
  <pre><code>y    | 03/02/2016 | 11:30:30
  z    | 03/03/2016 | 07:30:30
  </code></pre>
  
  <p>So basically I want to build a query which will give unique values for 'usage_date', with max 'usage_hour'. How can I build this query?</p>