The ER Model in Concept Maps

by K. Yue

Example

The goal of this example is to eventually construct a concept map (CM) for the ER model. This example shows the first few steps in the iterative refinement process.

We start with a very simple high level CM for "database system."

Notes:

• There are only three concepts.
• Highlight that DB systems are for finding solutions to problems.

We refine and expand our CM model iteratively.

Notes:

• Promote "requirement" from a link (relationship) to a concept.
• Concepts are more flexible. It can have links. A link cannot has a link.
• Concepts and relationships become more specific in interactive refinement: E.g. "requirements" becomes "data requirements."

Notes:

• The key concept of data model is added.
• Need to promote "data requirements" to a concept in the previous step for it to have a link with the concept "data model."

Notes:

• Once the context is clear, the central concept of "ER Model" is introduced as a "data model" that "captures" "data requirements."
• An ER model is eventually implemented (enforced) by a database system.

Notes:

• UML is introduced to contrast with the ER model.
• Because of its more general nature, UML model is not only a data model but can support other models.

Details of ER model can now be added.

Notes:

• The two most important components of an ER model are added first.
• By adding them, future focus points are open up for the next iterative refinement step. Examples:
  • What is an entity?
  • How should we use entities to capture data requirements?
  • What is a relationship?
  • How should we use relationships to model data requirements?
  • How do we form relationships between entities?
• Other components and details, such as attributes, can be added iteratively.