Data modelling & systems analysis

There are many graphical tools available to construct models of data flow. What follows is an attempt to summarise many of the data modelling tools available to the systems designer. For detailed coverage of the portions, I suggest you refer to the original references. [eg. Parker]

Graphical tools

When analysing a system using an Information Engineering approach, some of the steps are;

Requirements Analysis

Information Analysis
Data Flow Diagram

Data Model
Data Dictionary
Entity Relationship Diagrams

Procedure formation
Process diagrams (eg. Structure Diagrams)

Data Use Analysis
Input procedures
Output destinations (who gets what!)

Introduction to data modelling

Once the model is complete, coding and implementation may occur.

In modern methodologies, particularly with the use of Fourth Generation Languages and CASE tools, this process should be iterative.

That is, as the system is being designed, users are commenting and modifying the system so that the system ultimately matches their requirements.

Note that these requirements may be dynamic, that is be changing while the system is being designed. (For example, new Government legislation is introduced.)