getNonAggregates example

    // Add all the tables to the query via joins. We assume all LEFT joins.     foreach ($this->tableQueue as $table) {
      if (is_object($table['join'])) {
        $table['join']->buildJoin($query, $table, $this);
      }
    }

    // Assemble the groupby clause, if any.     $this->hasAggregate = FALSE;
    $non_aggregates = $this->getNonAggregates();
    if (count($this->having)) {
      $this->hasAggregate = TRUE;
    }
    elseif (!$this->hasAggregate) {
      // Allow 'GROUP BY' even no aggregation function has been set.       $this->hasAggregate = $this->view->display_handler->getOption('group_by');
    }
    $groupby = [];
    if ($this->hasAggregate && (!empty($this->groupby) || !empty($non_aggregates))) {
      $groupby = array_unique(array_merge($this->groupby, $non_aggregates));
    }