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Hello, I’m starting the study on conceptual modeling and relationship entity until I came across a question and so far not found similar examples.
To simplify, I have two entities, TIME and START. For each instance of START, I need to have two instances of TIME related to it.
With this in mind I put together the diagram of this image, which gave me the doubt, because I didn’t see any similar example, so I wanted to know if it is like this or has another way to solve this scenario?
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Friend then, I don’t have a diagrammer on my pc because I formatted so I did it on Paint anyway. The thing is that you don’t need to have two games you can put straight type on the table match. But the same is right to create a own table for game type and connect with the match.
Your answer is not in accordance with the conventions of Entida-relationship diagrams (ERI). Consider following some notation, such as UML and correct your answer: https://www.devmedia.com.br/modelo-entidade-related-mer-e-diagram-entidade-relationship-der/14332
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Hello my noble friend all right? I suppose our friend wanted to pass you this diagram. We see that the entity "match type" is weak compared to match, so it has its code id. good luck!!
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I enjoyed the case study, but I think it still needs more attributes for the entities. For example, what makes a game unique, in addition to the teams participating, are the time, date, score/goals, place where it is happening, etc. Yes, you are going the right way. I still think you should ask a clearer question: what is your doubt specifically?
– user41210
I didn’t get to put all the attributes, but they exist like the ones you suggested. I only tried to focus on the case of two relationships between two classes, after all most examples have a relationship between two classes, or have an associative entity in relationships n:m. My question is: From the conceptual model’s point of view, these two relationships between two classes is valid?
– Heminio Gurgel
I don’t think so, but that’s what I always say, depending on the requirements we don’t know. What’s in charge is always the requirement, is the specific case, is not a silly rule created by someone of what is right or wrong.
– Maniero
I agree in part with @Maniero. Since the rules have attributes between them, the relations, in teria, should refer to the attributes and not, as we classically refer, to the entities themselves. On the other hand, it lacks completeness when it comes to the requirements of the model. I recommend reading the following article: http://academic2.strose.edu/math_and_science/avitabij/cis503fall06/answers3.htm
– user41210
Thank you, the article has the exact example I needed to dispel doubt, which was only if there can be more than one relationship between two entities. !
– Heminio Gurgel