protected function _parseConditionSign($conditionSign = null) {
		$result = '';
		if (empty($conditionSign)) {
			return $result;
		}

		$conditionSign = (string)mb_convert_case($conditionSign, MB_CASE_LOWER);
		switch ($conditionSign) {
			case 'gt':
				$result = '>';
				break;
			case 'ge':
				$result = '>=';
				break;
			case 'lt':
				$result = '<';
				break;
			case 'le':
				$result = '<=';
				break;
			case 'ne':
				$result = '<>';
				break;
			case 'eq':
			default:
				$result = '';
		}

		return $result;
	}