I took an open source product ... and forked the code, and ... added ... some extra tables in the MySQL database ... I would like to load my data back into the mainstream product. How would I do that?
If I understand you correctly, you took a project and modified the database locally as you worked with it. Now you want to take your changes and apply them to what's, presumably, a running instance in production that doesn't have the changes yet.
Very briefly, since there's not that much info, you'll need to do the following:
- schedule some downtime for the current production instance;
- make the changes to the production database (i.e. run the SQL queries);
- apply the code changes that make use of the updated database;
- add/move any table data as necessary, if needed/applicable;
- verify that things are working correctly;
If what you're trying to do is get your changes into the upstream project itself (i.e. have your code merged into their codebase, etc), then you'll have to consult with the contribution guidelines for that particular project.