Single view over multiple tables

In my effort to learn rails, I’m writing a personal Information
Management “system”. So, something where I can track passwords, credit
cards, ssn, drivers license, etc. What I have done, and perhaps not
correctly, is created a table for each category.

I want to create a master list page. One view that displays all the
data from the various tables by category. Do I fail as a database
designer or is there a way to make this happen easily? Is there a
tutorial I might benefit from?

I started off creating a categories, passwords and creditcards table. I
can enter data into all three. I have the relationship between
categories and passwords and categories and creditcards working just
fine. I started to create a join between creditcards_passwords
thinking that I could then create the scaffold and view from there that
would allow me to see all my password and credit card entries in one
combined list, but Iâ??m feeling like I might be way off the reservation
on this approach.

Thanks for the help.
K.