What should the dynamic query for the following SQL string be?
$query = db_select('sites', 's')
  -&gt;fields('p', array('id', 'name'))
  -&gt;groupBy('p.id');

$query-&gt;addExpression('GROUP_CONCAT(s.name)', 'site_list');
$query-&gt;join('publications', 'p', 's.id = p.site_id');