Only if they're randomly named.
> Without seeing something else, e.g., the code, a flowchart, or other diagrams it is impossible to predict what the program actually does.
Seeing a table named "invoices", which has a column named "user_id" that is a foreign key for table "user" doesn't give you at least a few clues about the business logic there?
Seriously, I want to see an example (choose an open source project) of a project where the data structures don't give any clue to what the business logic is.
Once you go looking for that example, you'll see why the data structures are more revealing than looking at the code.