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244 Part Two Information Technology Infrastructure

Program-Data Dependence
Program-data dependence refers to the coupling of data stored in files and the
specific programs required to update and maintain those files such that changes
in programs require changes to the data. Every traditional computer program
has to describe the location and nature of the data with which it works. In a
traditional file environment, any change in a software program could require a
change in the data accessed by that program. One program might be modified
from a five-digit to a nine-digit zip code. If the original data file were changed
from five-digit to nine-digit zip codes, then other programs that required the
five-digit zip code would no longer work properly. Such changes could cost
millions of dollars to implement properly.

Lack of Flexibility
A traditional file system can deliver routine scheduled reports after extensive
programming efforts, but it cannot deliver ad hoc reports or respond to unantic-
ipated information requirements in a timely fashion. The information required
by ad hoc requests is somewhere in the system but may be too expensive to
retrieve. Several programmers might have to work for weeks to put together the
required data items in a new file.

Poor Security
Because there is little control or management of data, access to and dissemina-
tion of information may be out of control. Management may have no way of
knowing who is accessing or even making changes to the organization’s data.

Lack of Data Sharing and Availability
Because pieces of information in different files and different parts of the
organization cannot be related to one another, it is virtually impossible for
information to be shared or accessed in a timely manner. Information cannot
flow freely across different functional areas or different parts of the organi-
zation. If users find different values of the same piece of information in two
different systems, they may not want to use these systems because they cannot
trust the accuracy of their data.

6.2 THE DATABASE APPROACH TO DATA
MANAGEMENT

Database technology cuts through many of the problems of traditional file
organization. A more rigorous definition of a database is a collection of data
organized to serve many applications efficiently by centralizing the data and
controlling redundant data. Rather than storing data in separate files for each
application, data appears to users as being stored in only one location. A single
database services multiple applications. For example, instead of a corporation
storing employee data in separate information systems and separate files for
personnel, payroll, and benefits, the corporation could create a single common
human resources database.

DATABASE MANAGEMENT SYSTEMS

A database management system (DBMS) is software that permits an
organization to centralize data, manage them efficiently, and provide access

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