PURPOSE OF THESE FACTS :-
These FACTS define business requirements which the Database must support.
They form the basis for agreement between the User and the Database Designer and are
written in a form of structured English which is clear and unambiguous.
The Draft FACTS have been defined and are detailed here ...
A. The Area being Modelled is :-
An e-Commerce Web Site for a specialist Bookseller.
B. The Things of Interest, ('THINGS'), include :-
B.1 Books
B.2 Book Categories
B.3 Contacts
B.3 Customers
B.4 Orders
B.5 Order Items
B.6 Suppliers
C. These THINGS are Related as follows :-
C.1 A CUSTOMER can place zero or many ORDERS.
This provides flexibility where a CUSTOMER calls to register an interest,
or places an ORDER which is subsequenlty cancelled.
C.2 An ORDER is always associated with one and only one CUSTOMER.
C.3 An ORDER always has one or more ORDER_ITEMS.
C.4 A SUPPLIER can supply one or more BOOKS.
C.5 C.6 A BOOK can be in one or many BOOK_CATEGORIES.
C.6 A BOOK_CATEGORY can have zero or many BOOK_SUB_CATEGORIES.
C.7 A BOOK_SUB_CATEGORY can belong to one and only one BOOK_CATEGORY.
D. Other Characteristics of these THINGS include
D.1 A BOOK has a PRICE
D.2 A BOOK has a PUBLICATION_DATE.
E. Sample Data includes :-
To be determined
F. Typical Enquiries include :-
F.1 What BOOKS do we have about RAILWAYS ?
F.2 Do we have any BOOKS by Williams Faulkner ?
G. NOTE :
G.1 The proposed design can easily be extended to selling things
other than Books by replacing the BOOKS Table by an 'ITEMS_FOR_SALE' Table.
However, a BOOKS Table will still be useful because many data items are specific
to BOOKS, such as ISBN number, and it's better to avoid a coding scheme which
is designed to provide generality at the expense of ease of understanding.
Barry Williams
Principal Consultant
Database Answers
20th. January 2001
