Database Reference
In-Depth Information
checking the work you performed on the fields to ensure that you didn't accidentally miss
anything, and ensuring that each table structure is properly defined. Next, youestablish the
appropriate keys for each table. Your main task is to ensure that each table has a properly
defined primary key; this particular key uniquely identifies each record within a table.
The final step in this phase is to establish field specifications for each field in the database.
Here you conduct interviews with users and management to help you identify the specific
field characteristics that are important to them and review and discuss any characteristics
with which they may be unfamiliar. After you've completed these interviews, you define
and document field specifications for each field. You then review the table structures and
field specifications with users and management once more for possible refinements. The
tablestructuresarereadyforthenextphaseonceyoucompletetherefinements(ifany)that
you identified during the review.
Determining and Establishing Table Relationships
The fourth phase of the database design process involves establishing table relationships.
You conduct interviews with users and management once again, identify relationships,
identify relationship characteristics, and establish relationship-level integrity.
Working with users and management is a prudent exercise because they can assist you in
identifyingrelationshipsamongthedata.Youcannotpossiblybefamiliarwitheveryaspect
of the data your organization uses, so leveraging whatever knowledge they have about the
data they use will be very beneficial to you.
After you've identified the relationships, you establish a logical connection between the
tables in each relationship with a primary key or with a linking table. What you actually
usedependsuponthetypeofrelationshipyou'reestablishingbetweenthetables.Next,you
determine the type of participation and degree of participation for the tables in each rela-
tionship.Insomecases,theseparticipationcharacteristics willbeobvioustoyouduetothe
nature of the data stored in the tables. In other cases, you'll base the participation charac-
teristics on specific business rules.
Determining and Defining Business Rules
Determining and defining business rules is the fifth phase of the database design process.
During this phase, you'll hold interviews, identify limitations on various aspects of the
database, establish business rules, and define and implement validation tables.
The manner in which your organization views and uses its data will determine a set of lim-
itations and requirements that you must build into the database. Your interviews with users
andmanagementwillhelpyouidentifythespecificconstraintsyouwillimposeonthedata,
