protected function param($param, bool $enclose = true): string
	{
		if($param instanceof Raw)
		{
			return $this->raw($param);
		}
		elseif($param instanceof Subquery)
		{
			return $this->subquery($param, $enclose);
		}
		elseif($param instanceof DateTimeInterface)
		{
			$this->params[] = $param->format(static::$dateFormat);

			return '?';
		}

		$this->params[] = $param;

		return '?';
	}