    public static function is_loggedin () {
        $username = Session::val('username');
        if(isset($username)) {
            $v = true;
        }else{
            $v = false;
        }
        return $v;
    }

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.