Databases Reference
In-Depth Information
Chapter 14
Building a
Data Model
Candace C. Fleming and Barbara von Halle
D
ATA
MODELING
IS
A
TECHNIQUE
FOR
CLEARLY
REPRESENTING
BUSINESS
INFORMATION
STRUCTURES
AND
RULES
AS
INPUT
TO
THE
DATABASE
DESIGN
.
PROCESS
At the heart of data modeling is an appreciation of data as a valu-
able resource for a business organization. Data modeling is a philosophy
(as well as a technique) for recognizing and documenting the fact that busi-
ness information has an existence, independent of how it is accessed, who
accesses it, and whether or not such access is computerized.
The following is a list of business facts that can be represented through
a data model:
• Customers place orders.
• People eat ice cream cones.
• Some people pay bills on time.
• Some people do not pay bills on time.
• Some people do not pay bills at all.
These facts are true even if there is no current need to produce reports
or answer queries about them. Recognizing such facts, identifying those
that are significant to a user's business, and developing a corresponding
data model enable the user to accommodate access requirements through
database technology. Regardless of whether such facts (or some subset of
them) become components of the actual database, a data model often can
help people understand specific aspects of the business.
This chapter provides an overview of a methodology for logical data modeling.
DATA MODELING CHARACTERISTICS
Data modeling methodology has several important characteristics that
contribute to its effectiveness. First, it is an entirely data-driven process
(i.e., it is unbiased by particular information system requirements or
technological considerations). A data-driven model facilitates greater sta-
bility and flexibility within subsequent database design. Second, the
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