How to create sitemaps to all companies stored in database

It's nice that you want to do a thing; telling us about it, however, is rarely going to get you any help. You will most likely only get useful responses when you actually ask a question.

Furthermore, it will also help if you demonstrate what you have already done in trying to solve your problem. While pretty much everybody here is glad to help if they can, nobody likes to be asked to do your work for you.