Importing Joomla 1.5.23 to Drupal 7 by using Feeds
I've never considered how you would use Feeds to import from a database, but it works great for migrating content when that content is in a "feed".

If you have to use the DB, then there is Feeds SQL and Feeds DB, but I think both require you to write a query. That said, if you are using phpMyAdmin then when you "open" any of those tables phpMyAdmin will show the query it's running.

If you are able to expose your content as an xml/rss feed, a JSON feed, , or etc. then thing become very straight forward.

Using the Feeds Preview module may help you get your mapping correct.

You should be able to import the node alias (path) along with the content.