title: How to access to fields of a record type in postgresql without knowing their names?
body: <p>I'm programming a PL/pgSQL function with this:</p>
  
  <pre><code>cols_to_select := according to a set of rules, we get the name of the columns
  
  FOR I IN EXECUTE 'SELECT '||cols_to_select||' FROM tabl' LOOP
    -- how to access to fields of record I without knowing their names?
    -- 
  
  END LOOP;
  </code></pre>