Chapter 2 Conceptual Data Model Basics

What is a CDM?

A Conceptual Data Model (CDM) represents the overall logical structure of a database, which is independent of any software or data storage structure. It gives a formal representation of the data needed to run an enterprise or a business activity, and will often contain data objects not yet implemented in the physical database.

When designing a database, the design process normally starts at the conceptual level, where you do not need to consider the details of actual physical implementation.

A CDM allows you to:

Represent the organization of data in a graphic format to create Entity Relationship Diagrams (ERD)
Verify the validity of data design
Generate a Physical Data Model (PDM), which specifies the physical implementation of the database
Generate an Object-Oriented Model (OOM), which specifies an object representation of the CDM using the UML standard
Generate another CDM, to create another model version in order to represent different design stages

For more information on ERD, see James Martin's Information Engineering , Prentice Hall, 1990 (three volumes).