            $length = iconv_strlen($s, $encoding) + $length - $start;
            if ($length < 0) {
                return '';
            }
        }

        return iconv_substr($s, $start, $length, $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.