title: PostgreSQL sum without aggregation
body: <p>I have one table:</p>
  
  <pre><code>a b
  x 5
  y 20
  z 10
  </code></pre>
  
  <p>i want to have a sum of column b but without aggregation, thus i would get this as result:</p>
  
  <pre><code>a b  c
  x 5  35
  y 20 35
  z 10 35
  </code></pre>
  
  <p>This should be possible right? How this the Select comming from the table above?</p>