title: using a case when to identify if a timestamp = 'null'
body: <p>I'm trying to construct a case when statement in BQ on a timestamp column called version_end_ts.  Specifically I want my statement to read:</p>
  
  <p>case when version_end_ts = 'null' then 'active' else 'past' end as status</p>
  
  <p>Problem is BQ is is telling me that it "Could not cast literal "null" to type TIMESTAMP".   Is there a way to return a positive flag in my case when if the timestamp is missing?  I searched high and low and couldn't find an answer to this one.  </p>
  
  <p>Thank you in advance for your help.</p>
  
  <p>Brian</p>
  
  <p><a href="https://i.stack.imgur.com/fB3QO.jpg" rel="nofollow noreferrer">version_end_ts</a></p>