// if field not set, builds template from sqlForPath and comparator(Id)
	function getSqlTemplate() {
		if ($this->sqlTemplate) return $this->sqlTemplate;

		$template = '';
		$comp = $this->get('comparator');
		if (!$comp) throw new PntError('No comparator '. Gen::toString($this));
		$sqlOperator = $comp->getSqlOperator();
		if ($sqlOperator == '=' && $this->value1 === null)
			$sqlOperator = 'IS';
		if ($sqlOperator == '!=' && $this->value1 === null)
			$sqlOperator = 'IS NOT';
		if ($comp && ($comparatorPreceder = $comp->get('preceder')) )
			$template .= "$comparatorPreceder ";
		$template .= "(\$columnName $sqlOperator ?";
		if ($comp && ($comparatorAddition = $comp->get('addition')) )
			$template .= " $comparatorAddition ?";
		$template .= ")";

		return $template;
	}