title: Aggregating results from SPARQL query
body: <p>I'm querying a dataset of tweets: </p>
  
  <pre class="lang-sql prettyprint-override"><code>SELECT * WHERE {
    ?tweet smo:tweeted_at ?date ;
           smo:has_hashtag ?hashtag ;
           smo:tweeted_by ?account ;
           smo:english_tweet true .
    FILTER ( ?date &gt;= "20130722"^^xsd:date &amp;&amp; ?date &lt; "20130723"^^xsd:date )
  }
  </code></pre>
  
  <p>If a tweet has multiple hashtags, there is one row in the result set per hashtag.  Is there any way for me to aggregate the hashtags into an array instead?</p>