The database from Drupal (depending on the version) is very complex and all the settings you made in Drupal (content types, modules installed, etc) are all kept in there using different tables. Some of your personal data would be under table "node". Any content you add to Drupal will have an entry in there. Also "users" would have all your users listed, and so on... But if you change the content types (add fields) then there will be more tables you need to JOIN to "node" to see the data. There is a module called "Views" that will help you find all the data (you probably know about it)
To answer your question, there are multiple tables that hold your data so it's not easy to find them depending on how complex the site is.
Remember that Drupal is open source so you would not be able to change a licence fee for it if you want to distribute it to others.
Hope this answers your question.