title: Postgresql ERROR: cannot drop columns from view
body: <p>I'm new to postgresql. Can anyone suggest the reason and solution to this error? However it works if I select an extra sum(s.length) but i don't won't this in my results.</p>
  <p>code:</p>
  <pre><code>create or replace view q1(&quot;group&quot;,album,year)
  as
  select g.name, a.title, a.year
  from Groups g, Albums a, Songs s
  where a.made_by = g.id and s.on_album = a.id
  group by a.title, g.name, a.year
  order by sum(s.length) desc 
  limit 1
  ;
  </code></pre>
  <p>Error message:</p>
  <blockquote>
  <p>ERROR:  cannot drop columns from view</p>
  </blockquote>