Customers have thier own life and Books also have their own life
If you have denormalized data on to the customer table this is no longer true. Books have their own life, except when their data has to be kept in sync with data on customer records (delete or update a book and you have to update costomer records). I still can't see what you gain by modelling this the way you have. If it is a many to many relationship you are modelling, whould a ternery join table not be a better approach?
If you can't do anything about the data model, and this is a read only view only view, I'd suggest you create a named query for it rather than mapping the pseudo-association.