title: Empty group by and nested construct
body: <p>I have two questions regarding (i) group by clauses and (ii) nested construct SPARQL queries.</p>
  <p>(i) Is it possible to formulate a SPARQL query with an empty GROUP BY clause
  i.e. something like GROUP BY (), where the keyword &quot;GROUP BY&quot; appears in the query with an empty set of values.</p>
  <p>(ii) Could a nested query be a &quot;CONSTRUCT SPARQL query&quot;, the results of which will be then used in an outer SELECT clause, i.e.</p>
  <pre><code>SELECT 
  WHERE {
  {
  CONSTRUCT ...
  }
  }
  </code></pre>