In this book, we're not dealing on the entire application development process but concentrating on how to create a database design that models business needs.
As you've just seen, the business objects in particular dictate the database's tables. But the database also is influenced heavily by business rules because they govern things such as data types, allowable values, and relationships between tables.
Relationships are probably the single greatest challenge for the system architect: not only are relationships the most complex things to design, but if you define them wrongly, it can be even more difficult to sort out things later.
Apart from making sure that the business need is suitably represented, the designer needs ...