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.