title: How to get records from db where column = ? OR IS NULL
body: <p>I have a view where on the <code>created_at</code> column I have <code>dates</code> and there are few rows where the created_at column is empty.</p>
  
  <pre><code>`dates = [Date.today, nil]`
  `Dashboard.where(created_at: dates)`
  </code></pre>
  
  <p>I tried this, is working fine, but is it the best way?</p>