How to deal with the OpenCart Database?

Question

MySQL

There is a domain with an active store (opencart 1.5.4.1), and there is a subdomain where I am building a new version of the same store on opencart 2.3 . I plan to buy the theme. And when on the subdomain there will be a completely ready site filled with goods, instead of the outdated one, upload it to the old domain. Why not just update within the domain from version 1.5 to 2.3 - because the old site was added by the old owners. And there now in the guts the devil will break his leg. I'm afraid that when updating, a lot of problems will come out, so I'm doing it from scratch on a subdomain.
The question is: How to do everything without unnecessary problems?
1) Database - create a new one for the subdomain (and then specify it when you transfer files to the domain)? Or specify the old one when creating a site on a subdomain?

Answer 1

The database structure is different in 2.3 and 1.5.
You will need to develop everything on a subdomain, and then transfer the product to a new database.