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Chapter 6 Foundations of Business Intelligence: Databases and Information Management 245

to the stored data by application programs. The DBMS acts as an interface
between application programs and the physical data files. When the applica-
tion program calls for a data item, such as gross pay, the DBMS finds this item
in the database and presents it to the application program. Using traditional
data files, the programmer would have to specify the size and format of each
data element used in the program and then tell the computer where they
were located.
The DBMS relieves the programmer or end user from the task of under-
standing where and how the data are actually stored by separating the logical
and physical views of the data. The logical view presents data as they would be
perceived by end users or business specialists, whereas the physical view shows
how data are actually organized and structured on physical storage media.
The database management software makes the physical database available
for different logical views required by users. For example, for the human
resources database illustrated in Figure 6.3, a benefits specialist might require
a view consisting of the employee’s name, social security number, and health
insurance coverage. A payroll department member might need data such as the
employee’s name, social security number, gross pay, and net pay. The data for
all these views are stored in a single database, where they can be more easily
managed by the organization.
How a DBMS Solves the Problems of the Traditional
File Environment
A DBMS reduces data redundancy and inconsistency by minimizing isolated
files in which the same data are repeated. The DBMS may not enable the
organization to eliminate data redundancy entirely, but it can help control
redundancy. Even if the organization maintains some redundant data, using
a DBMS eliminates data inconsistency because the DBMS can help the
organization ensure that every occurrence of redundant data has the same
values. The DBMS uncouples programs and data, enabling data to stand

FIGURE 6.3 HUMAN RESOURCES DATABASE WITH MULTIPLE VIEWS

A single human resources database provides many different views of data, depending on the
information requirements of the user. Illustrated here are two possible views, one of interest to a
benefits specialist and one of interest to a member of the company’s payroll department.

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