title: Bigquery: Getting first day of the week/month in standard SQL
body: <p>In Bigquery's <strong>legacy</strong> SQL, I can get the start of week for a date by using</p>
  
  <pre><code>SELECT DATE((UTC_USEC_TO_WEEK(TIMESTAMP_TO_USEC(TIMESTAMP('2017-04-13 20:58:06 UTC')), 0)))
  </code></pre>
  
  <p>which returns <code>2017-04-09</code>.</p>
  
  <p>Is there a way to do this in BigQuery's <strong>standard</strong> SQL? There doesn't seem to be any equivalents for <code>UTC_USEC_TO_WEEK</code> and <code>UTC_USEC_TO_MONTH</code>.</p>