Moving Files

How can I successfully develop a WP site in one folder on a server and then copy the files over to the root of my domain name?

Let’s say I’m developing in a folder called http://www.domainname.com/wp but when I’m done I want to migrate the files to http://www.domainname.com.

If I simply download everything and copy it back to the root of the domain name, will it work? Or will it screw up the connection to the database?

Thanks.