title: How to cut a datetime and remain the time part only
body: <p>I have data like below:</p>
  
  <pre><code>2018-04-01 00:12:45.823 
  2018-04-01 00:12:49.897 
  2018-04-01 00:12:56.207
  </code></pre>
  
  <p>How to cut them only remain:</p>
  
  <pre><code>00:12:45.823
  00:12:49.897
  00:12:56.207
  </code></pre>