How to pass GET through htaccess?

Question

htaccess

Hello.
The user enters the page using the link:
http://reg.site.ru/?code=123abc
123abc - everyone will have their own.
The site file contains htaccess, which should redirect the request to another site:
Redirect 301 / https://site2.ru/?code=123abc
How to compose htaccess to pass code=123abc to GET?

Answer 1

Through{REQUEST_URI}