public function appendPsTo(&$sb, array &$params)
    {
        $sb .= str_repeat('(', count($this->clauses));

        $this->dispatchPsHandling($sb, $params);

        foreach ($this->clauses as $key => $clause) {
            $sb .= $this->conjunctions[$key];
            $clause->appendPsTo($sb, $params);
            $sb .= ')';
        }
    }