Database Reference
In-Depth Information
11. Business Rules
You are remembered for the rules you break.
—G
ENERAL
D
OUGLAS
M
AC
A
RTHUR
Topics Covered in This Chapter
Throughout the database design process, you've performed tasks that helped to establish
various levels of data integrity. You've established table-level integrity, field-level integrity,
and relationship-level integrity thus far. In doing so, you've ensured that the table and field
structures are sound, that data entered into the fields will be consistent and basically valid,
and that relationships are meaningful and properly established. In this chapter you'll learn
how to establish the final component of overall data integrity:
business rules.
What Are Business Rules?
A
business rule
is a statement that imposes some form of constraint on a specific aspect of
the database, such as the elements within a field specification for a particular field or the
characteristics of a given relationship. You base a business rule on the way the organization
perceives and uses its data, which you determine from the manner in which the organization
functions or conducts its business.
An important aspect of any design process is making choices. In database design, for ex-
ample, youmust choose which data tostore inthe database; youwould notnecessarily want
or need to store every last piece of data the organization might
possibly
use. The data you
finally choose to store and how you decide to store it will be determined by the way the or-
ganization uses its data. A hospital may wish to store times of various events to the second,
whereas a warehouse requires only the date for any given event.
