title: How can i get number of quarters between two dates in PostgreSQL?
body: <p>I have MS SQL function <code>DATEDIFF</code></p>
  
  <pre><code>SELECT DATEDIFF(QQ, 0, '2018-09-05')
  </code></pre>
  
  <p>that returns 474(integer). </p>
  
  <p>What is PostgreSQL equivalent of this function ?</p>