Android : How To Add User Customized Data To Database?

I am trying to design a sqlite database that will store notes. Each of these notes will have common fields like title, due date, details, priority, and completed.

In addition though, I would like to add data for more specialized notes like price for shopping list items and author/publisher data for books.

I also want to have a few general purpose fields that users can fill with whatever text data they want. How can I design my database table in this case?

I could just have a field for each piece of data for every note, but that would waste a lot of fields and I'd like to have other options and suggestions.