Database Reference
In-Depth Information
data structures, or relationships. You then establish and document these specifications as
business rules.
Theinterviewsyouconductwithuserswillreveal
specific
limitationsonvariousaspectsof
the database. For example, a user working with an order processing database is very aware
of specific details, such as the fact that a ship date must occur later than an order date; that
there must always be a daytime phone number; and that a shipping method should always
be indicated. Your interviews with management, on the other hand, reveal
general
limita-
tions on various aspects of the database. For example, the office manager for an entertain-
ment agency is familiar with general issues such as the fact that an agent can represent no
more than 20 entertainers and that promotional information for each entertainer must be
updated every year.
Next, you define and implement validation tables as necessary to support certain business
rules.Supposeyoufindthatcertain fieldshaveafiniterangeofvaluesbecauseoftheman-
ner in which your organization uses them. You can use validation tables to ensure the con-
sistency and validity of the values stored in those fields.
The level of integrity that business rules establish at this point is significant because it
relates directly to the way your organization views and uses its data. The organization's
perspective on the data will change as the organization grows, which means that the busi-
ness rules must change as well. Determining and establishing business rules is an ongoing,
iterativeprocess,andyoumustbeconstantlydiligentifyouaregoingtomaintainthislevel
of integrity properly.
Determining and Defining Views
Thesixthphaseofthedesignprocessinvolvesdetermininganddefiningviews.Hereyou'll
conduct interviews (once again), identify various ways of working with the data, and es-
tablish the views.
Youidentify thetypesofviewsyouneedtobuildinthedatabase byinterviewing usersand
management and determining how they work with their respective data. You may find, for
example, that many users require detailed information to perform their work, while others
needonlysummaryinformationtohelpthemmakestrategicdecisionsfortheorganization.
Each group of users must access information in very specific ways, and you can use views
to accommodate these situations.
Next, you define the views you've identified during the interview process using the appro-
priate tables and fields, and establish criteria for those views that are required to retrieve
specific information. For instance, you would establish criteria for a view that must list
all customers located in Texas or a view that must display the total number of authorized
vendors (by city) in Washington.
