    private static function getSubpart($pos, $part, $haystack, $encoding)
    {
        if (false === $pos) {
            return false;
        }
        if ($part) {
            return self::mb_substr($haystack, 0, $pos, $encoding);
        }

        return self::mb_substr($haystack, $pos, null, $encoding);
    }
The software constructs all or part of an SQL command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended SQL command when it is sent to a downstream component.