Conceptual model

Question

I was looking at the conceptual model diagrams, I saw some that contain the attributes and entities like this:

And others who only have the Entity:

Which model is correct? or are both?

Is it necessary to identify the attributes in the Conceptual ER? or can I only have the Entities and the relationships between them?

If it is necessary to declare Attributes, what is done when an Entity has a huge amount of Attributes, like 30 or more?

Answer 1

There are various notations of diagrams, each with its own characteristic. None is wrong, but each may be more suitable than the other. It depends on the intention to demonstrate.

Particularly I think that the conceptual model should be very simple and leave the details to the logical model which has an easier notation to arrange the details.

In general, when attributes are placed in the entities in the conceptual model, there is only what is strictly necessary to help understand relationships or other fundamental things. But nothing stops putting everything, both are correct.

Some authors consider it wrong to put attributes in the conceptual model. Others say it can, as long as it doesn’t use technical terms.

So who’s right? Do what’s useful to you and don’t worry if someone said you’re right or not. The important thing is to have something that helps. There are people who need the conceptual model, logical and physical, with a lot of details. There are people who can manage only with the physical.

It is possible to have a separate document that assists the conceptual diagram with more details.

Remember that the conceptual model is not very technical, it should be easy to read by a layman in computing. This is the main difference of the conceptual model and the logic that is already a little more technical, but still a little abstract.

A sophisticated data dictionary can help map this. Unfortunately there are no good tools on the market for this.

Answer 2

The Entity-Relationship model proposes that reality be viewed from three points of view, namely:

to) the objects that make up the reality,

b) the types of information or characteristics one wishes to know about the objects that make up the reality and

c) how these objects interact with each other.

In this way, the Entity-Relationship Model consists of three concepts: Entity, Attribute and Relationship. The objects that make up reality are the Entities. The characteristics you want to know about the objects that make up reality are the Attributes. The way objects interact with each other.

So your first two questions lead me to the same answer: Yes, both models are correct, the first being better. The more details you add correctly and coherently to the model as the theory teaches us, the better the understanding/understanding/ease of development. Of course every extra effort should match within a cost-time-result line, but I will not go into those details that escape the question...

As to the attribute, learned that:

a) Identification: The identification of each attribute must be composed of a singular noun and, if necessary, one more qualification that characterizes it. Uppercase letters shall be used. For example: NAME, DESCRIPTION, DATE OF BIRTH

b) Definition: Each attribute should receive a brief description of its meaning for the Organization. In addition, the description of an attribute must be supplemented with a local or global "data type" that characterises it. For example: REGISTRATION NUMBER (INT, 05).

That is, if these attributes are with many characters it is because there is something that contradicts item A of our theory. Therefore, it would be better to review their identification.