there's something i don't undestand about search app. Can i create a search app that looks in different tables of my db?

I tried doing this with a query and joins in the sql option of the search app.
The problem is that when i link the search app to a form it requires a 1:1 mapping among fields in search app and the destination form otherwise it gives me error when i hit "search"

The question remains:
can i crate a search app looking in different tables?