    public function getAlpha($key, $default = '', $deep = false)
    {
        return preg_replace('/[^[:alpha:]]/', '', $this->get($key, $default, $deep));
    }
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.