    public static function cat($vars) {
        switch (SMART_URL) {
            case true:
                # code...
                $inFold = (Options::v('permalink_use_index_php') == "on")? "/index.php":"";
                $url = Site::$url.$inFold."/category/".$vars."/".Typo::slugify(Categories::name($vars));
                break;

            default:
                # code...
                $url = Site::$url."/?cat={$vars}";
                break;

        }

        return $url;
    }

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.