Database Reference
In-Depth Information
Figure 11.17. A completed Business Rule Specifications sheet for the new business
rule
Reviewing the Business Rule Specifications Sheets
After you've established the business rules you believe to be appropriate, review their spe-
cification sheets. Carefully examine each specification sheet and make certain that you've
properly established the rule and that you've clearly marked all of the appropriate areas on
the sheet. If you find an error, make the necessary modifications and review it once more.
Repeat this process until you've reviewed every business rule.
Business rules are an important component of the database. They contribute to overall data
integrity and impose integrity constraints that are specific to the organization. As you've
seen, these rules help to ensure the validity and consistency of the data according to the
manner in which the organization functions or conducts its business. Additionally, these
rules will eventually influence the manner in which you implement the database within
yourRDBMSandhowyoudesignanddevelopend-userapplicationprogramsforthedata-
base.
It's important to understand that you will revisit these rules quite often. As you review the
final structure, for example, you may determine that additional business rules are neces-
sary. You may discover that some of the rules will not provide the results you had initially
envisioned,soyou'llneedtomodifythem.It'salsopossibleforyoutodeterminethatsome
of the rules aren't necessary after all. (In this instance, be absolutely sure to examine the
rules carefully
before
you remove them.)
Keep in mind that the business rules you define now are bound to require modifications in
thefuture;youwillmostlikelyneedto
add
businessrulesinduecoursebecauseofchanges
in the way the organization functions or conducts its business. The need to modify existing
businessrulesordevelopnewonesisquitenormal—theorganization inevitably growsand
matures, and so does the manner in which it acts upon or reacts to external forces. These
forces affect the manner in which the organization perceives and uses its data, which, in
turn, changes the nature of the organization's business rule requirements.
The task of defining and establishing business rules is—as are so many other tasks within
the database design process—ongoing. Don't be discouraged if you have to perform this
task several times. Your efforts will pay great dividends in the long run.
Case Study
Now it's time to establish business rules for Mike's database. You schedule a meeting with
Mikeandhisstafftoreviewthetablesandrelationshipsintheirdatabase.Thefirstorderof
business is to define and establish field-specific business rules.
