Data Models

A data model is a collection of conceptual tools for describing data, data relationships, data semantics, and consistency constraints. In this part, we will learn two data models:

 The Entity-relationship model and

The Relational model.

          The entity-relational model is a high level data model. It is based on a perception of a real world that consists of a collection of basic objects, called entities and of relationships among those objects.

      The relational model is a lower level model. It uses a collection of a collection of tables to represent both data and relationships among those data. Now a day maximum database products are based on the relational model. Designers often formulate database schema design by first modeling data at a high level using E-R model and then translating it into the relational model.