title: Find timestamp difference in day in kdb
body: <p>How do you find the time difference in days between 2 timestamp in KDB?</p>
  
  <p>For eg.</p>
  
  <pre><code>q)d1:2019.02.16D12:16:00.000
  q)d2:.z.P
  </code></pre>
  
  <p>how to find difference between these two timestamp in days?</p>
  
  <pre><code>q)d1-d2 //in day
  </code></pre>