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In Chen notation multi-valued attributes are denoted by double eclipse(oval) and derived attributes are denoted by dotted eclipse(oval), but how they are denoted in crow foot notation?

Also how associative entities are denoted in crow foot?

2 Answers 2

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It's a common misconception that Crow's foot and Chen's notations are equivalent alternatives. They actually address different stages of modeling. Crow's foot notation is used in table diagrams (physical model) while Chen's notation is used in ER diagrams (conceptual model).

In physical models, derived and multivalued attributes are no longer indicated as such, but are implemented as columns or tables, respectively.

Derived attributes can be materialized in the physical model or calculated dynamically in the application. If materialized, they're indicated as normal columns, and the model can be complemented with triggers or expressions if required.

Multivalued attributes are implemented as a separate table with a composite key consisting of the entity and attribute value.

Conceptual model:

ER diagram with derived/multivalued attribute

Logical model:

Relational diagram with derived/multivalued attributes

Physical model:

Table diagram with derived/multivalued attributes

Associative entities are implemented exactly like relationships, since they are in fact just relationships that are the subject of further relationships.

Conceptual model:

ER diagram with associative entities

Logical model:

Relational model with associative entities

Physical model:

Physical model with associative entities

Note that in my physical model, I combined the Character and ThemeSong relationships due to having the same determinant (key).

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I was searching for the same answers for a while without much success and found @reaanb's answer quite satisfying and logical. But then I came across this in a book[A] and realised that in fact Crow's foot and Chen's notations are equivalent alternatives. Chen's is using a mindmap approach whereas crow's foot a tabular approach that's much similar to the class diagrams. The choice is yours. In a brainstorming session, it would be better to use Chen's style.

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A. Modern Systems Analysis and Design, 8th Edition, Joseph S. Valacich and Joey F. George

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