title: Binding parameter to Db::raw laravel query
body: <p>I've got the following raw query:</p>
  
  <pre><code>$results = Db::select( Db::raw("SELECT HOUR(created_at) as hour, COUNT(*) as count
                         FROM `visited`
                         WHERE created_at &gt;= DATE_SUB(NOW(),INTERVAL 16 DAY)
                         GROUP BY HOUR(created_at)") );
  </code></pre>
  
  <p>I need to parameterize the day interval, so I tried this:</p>
  
  <pre><code>$days = 16;
  $results = Db::select( Db::raw("SELECT HOUR(created_at) as hour, COUNT(*) as count
                         FROM `visited`
                         WHERE created_at &gt;= DATE_SUB(NOW(),INTERVAL :days DAY)
                         GROUP BY HOUR(created_at)", ["days" =&gt; $days]) );
  </code></pre>
  
  <p>But I am getting the following error:</p>
  
  <blockquote>
    <p>"SQLSTATE[HY000]: General error: 2031 </p>
  </blockquote>
  
  <p>Apparently the binding is not working. What am I doing wrong?</p>