Fig. 7.3.1 Separating detailed and summarized data.

After the granular data are identified, the next step is to “abstract” the data. The data are
abstracted to its highest meaningful level. The highest meaningful level is called an entity.

As a simple example of abstraction, suppose a corporation has female customers, male
customers, foreign customers, corporate customers, and governmental customers. The
data model creates the entity known as “customer” and wraps all of the different types of
customer together.

Or suppose the company produces sports cars, sedans, SUVs, and trucks. The data model
abstracts the data into the entity—vehicle.

The ERD

Chapter 7.3: Data Modeling for the Structured Environment