COBOL for the 21st Century

Chapter 3. The DATA DIVISION

OBJECTIVES

To familiarize you with

1. Systems design considerations that relate to programming.

2. The ways in which data is organized.

3. The rules for forming data-names and constants in COBOL.

4. How input and output files are defined and described in the DATA DIVISION.

5. How storage can be reserved for fields not part of input or output, such as constants and work areas.

SYSTEMS DESIGN CONSIDERATIONS

The Relationship Between a Business Information System and its Programs

Programs are not usually written as independent entities. Rather, they are part of an overall set of procedures called a computerized business information system. Each program, then, is really only one part of an information system.

A systems analyst is the computer professional responsible for the design of the overall computerized business information system. Thus, if the sales department of a major company is not running smoothly or is too costly to operate, the company's management may call on a systems analyst to design a more efficient business information system. Because such a design would typically include computerization of various aspects of the department's functions, the systems analyst should have considerable computer expertise.

The systems analyst first determines what the outputs from the entire system should be and then designs the inputs necessary to produce these outputs. The analyst also determines what programs are required to read input and to produce the required output. Each set ...