Is it posible to customise a new theme in a test subdomain using the same database?

[northweb]

Hi

I'm a novice on these things sorry and this may be a silly question but I want to customise a new theme for an existing site before making the changes live. The current site needs to remain working exactly as it is in the meantime - ideally with posts still being added in the meantime. I'd like to use all the content from the current site when customising the new look so I can get all the widgets in the right place etc. I've installed Wordpress on a subdirectory of the existing domain and am now at the Wordpress Setup Configuration File window.

Can you advise whether it will work if I enter the database/SQL info from the live site even if it's in a different directory.

Thanks