Is ERD considered a kind of UML diagram?

Question

Are Entity Relationship Diagrams(ERD\'s) considered a type of UML diagram or are they a separate thing?

Answer 1

I have a different opinion to Andy. In UML Class Diagrams you describe relationship between two classes. With ERD you can talk about relationships between more than two entities.

This is the reason why the cardinality in Chen-Diagrams are on opposite site compared to UML Class Diagrams. You have to think about number of relations for every single entity.

Let's take a look at one simple example:

In this little example every supplier must be in relationship with at least one delivery. But there can be items not being delivered and projects without any deliveries.