Introduction to data model types

There are three data model types which differ by their level of detail:

Conceptual data model

The conceptual model is produced immediately after collecting the business requirements, and contains only the entities, relationships, and cardinality. This model is very easy to understand for business users who are heavily involved in defining it. Once it is completed and agreed upon, it is possible to move to the next, Logical data model.

Logical data model

The logical data model describes data in more detail. Each entity has attributes, with key attributes identified. The key attributes will form the primary keys and the foreign keys subsequently. Tables are usually normalised at this stage – before the actual implementation.

We will explain what normalisation means in one of the next lectures.

Physical data model

The physical data model represents how the model will be built in the database. When going from logical to physical model entities become tables, attributes become columns, data types have to be specified for each column, and primary and foreign keys are specified from the key attributes. The physical data model will be different for different databases.

Let’s explore each of these model types in more detail.

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