title: Convert SQL Datetime in a CSV to local datetime
body: <p>I have an export of all my signal text messages that I've decrypted. One of the stages was the conversion of an SQL database into a CSV, so I now have a large CSV that looks like this:</p>
  <p><a href="https://i.stack.imgur.com/LDGHG.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/LDGHG.png" alt="csv screenshot" /></a></p>
  <p>The fields are <code>_id</code>    <code>thread_id</code> date    <code>date_sent</code> <code>body</code> if that's not readable.</p>
  <p>I want to convert the <code>date &amp; date_sent</code> to something like <code>YYYY-MM-DD</code> but right now they're in a SQL format like <code>1568610000000</code> or <code>1590550000000</code>. Is there an easy way to convert these? I searched for about an hour before asking, but most q's are about how to convert a SQL into a CSV not how to manage exported SQL data in a CSV.</p>