The difference between an ER diagram and an Entiy binding diagram

Question

I am trying to create a conceptual data model using PowerDesigner , I found a conflie between two methods:

• Create two objects and the relationship between them
• Create an association and three objects and two relationships.

knowing that both methods give the same result when generating the physical data model

both methods are illustrated in the following figure.

Answer 1

Associations and relationships are different conceptual terms in Power-Designer.

An Association is the relationship between two or more objects .
Association may have attributes .

A Relationship is a relationship between two objects .
A Relationship has no attributes .

Association is a more general form of Relationship.

For instance:
Consider designing the many-many relationship between CustomerEntity and CreditGroupEntity
Designing a relationship using Relationship will create a third table by simply linking the CustomerEntity primary key and the CreditGroupEntity primary key.
When developing a relationship with the Association and adding the assign-date attribute to the association, a third table will be created that contains the ClientEntity primary key, CreditGroupEntity primary key, and date-destination fields.

The sample you used contains a 0-n cardinal with no attributes in association, so the difference is not visible.

Usually, association is used when the relation itself is an entity that has attributes.
A relationship that does not have attributes is implemented by the Relationship function.

Answer 2

Look at it as if you are trying to express something in different languages ​​or in different “versions” of the same language.

When you want to express “you idiot”, you can say “you idiot” or apply the art of typical British understatement, you can say something like “I think there are certain key elements to the problem that you seem to have missed.” These two sentences are not close anywhere, but they can very accurately express the same intended meaning.

Similarly with the ER chart. WHAT you want to express does not have a single unique [graphic in this case] way of expressing it. WHAT you want to express is semantics, the HOW you express is syntax. The same semantics can be expressed using different syntaxes, and this is not a mistake, it is a feature!