title: String to YYYY-MM-DD date format in Athena
body: <p>So I've looked through documentation and previous answers on here, but can't seem to figure this out.</p>
  
  <p>I have a <code>STRING</code> that represents a date. A normal output looks as such:</p>
  
  <p><code>2018-09-19 17:47:12</code></p>
  
  <p>If I do this, I get it to return in this format <code>2018-09-19 17:47:12.000</code>:</p>
  
  <pre><code>SELECT
  date_parse(click_time,'%Y-%m-%d %H:%i:%s') click_time
  FROM
  table.abc
  </code></pre>
  
  <p>But that's not the output I need. I was just trying to show that I'm close, but clearly missing something. When I change <code>click_time</code> to <code>date_parse(click_time,'%Y-%m-%d')</code>, it sends back <code>INVALID_FUNCTION_ARGUMENT: Invalid format: "2018-09-19 17:47:12" is malformed at " 17:47:12"</code></p>
  
  <p>So there's clearly something I'm not doing correctly to get it to simply return <code>2018-09-19</code>. </p>