title: how can I return the DBTIMEZONE name
body: <p>I ran</p>
  
  <pre><code>select dbtimezone, sessiontimezone
  from dual
  </code></pre>
  
  <p>which returned -04:00 and -06:00, respectively.</p>
  
  <p>I also ran </p>
  
  <pre><code>select
    TZ_OFFSET('US/Eastern') "EST_offset",
    TZ_OFFSET('America/Denver') "Mtn Time offset"
  from dual
  </code></pre>
  
  <p>which returned the same numbers.</p>
  
  <p>My question is, how can I convert "-04:00" into something like "US/Eastern"?  Is there a simple built-in function I am overlooking, or do I need to write my own CASE statement to create this relationship?</p>
  
  <p>Thank you!</p>