title: How to add a variable number of hours to a date in PostgreSQL?
body: <p><a href="http://wiki.postgresql.org/wiki/Working_with_Dates_and_Times_in_PostgreSQL">Apparently</a>, PostgreSQL doesn't have <code>DATEADD</code>, because you can just use the <code>+</code> or <code>-</code> operators.</p>
  
  <p>I need to add a number of hours to a date, which is accomplished like this:</p>
  
  <pre><code>date_field + interval '8.25 hour' 
  </code></pre>
  
  <p>Which is great, but I need the number of hours to come from a field in the table. Would be something like this:</p>
  
  <pre><code>date_field + interval start_time 'hour' 
  </code></pre>
  
  <p>I can't find anywhere how to do this. Is this actually impossible?</p>
  
  <p>I don't mind resorting to ugly hacks like taking the field value and dividing by 3600, multiplying by 86400. Whatever I need to do, but I haven't found any way to do that either.</p>