title: how to get relations (family relatives) in dataset?
body: <p>I have a database with the following fields:</p>
  <pre><code>name, father_name, grand_name, last_name
  </code></pre>
  <p>I want to view family relatives from the database</p>
  <p>i.e records with same <code>last_name</code> and <code>d1.grand_name = d2.father_name</code></p>
  <p>How to write this query ?</p>