DATA MODELING BASICS - Database Design and Development: An Essential Guide for IT Professionals - page 143

REAL-WORLD INFORMATION

Degree

SSNo

Name

Room
No
Office
Hours

Phone
Number

Student ID

Speciali-
zation

Major
Program

Name

SSNo
Address

E-mail
address

Phone
Number

Number of
Students

Class
Number

Room
Number

Meeting
Schedule

Class
Description

Figure 5-2 University database: real-world information requirements.

the real world that is of concern to the university? Figure 5-2 indicates a few of the
objects in the real world for the university. Note the information requirements about
these objects. These information requirements must be reflected in the generic data
model.
How do you determine the real-world information requirements? The analysts
on the database project for the university collect the requirements in the require-
ments definition phase. We covered that phase of DDLC in great detail. Recall how
the information requirements are recorded in the requirements definition document
as data groups. The collection of the data groups along with the descriptions of rela-
tionships and constraints forms the real-world information requirements for the
university.

Data Model as the Replica

We have noted the meaning of real-world information requirements. The following
are the requirements that must be satisfied by the proposed database. The database
must be implemented to serve the users, providing them with information as
required by them. The database must be designed so that it will contain data as
required by the users. And the design may be derived from a generic data model
that represents the information requirements.
The data model, therefore, is a replica or representation of the information
requirements. Examine the information requirements defined in the definition
phase of DDLC. Create a model—a data model—from the information require-
ments. That data model will then be a replica or representation of the information
requirements. Figure 5-3 illustrates how a data model is created from the informa-
tion requirements. Refer back to the Figure 5-2 and observe how the information
requirements about objects in the university's real world are represented in the data
model.