The discussion centers on the design of entity relationship models, specifically addressing whether repeated attributes should be shared among entities or duplicated. It is established that common attributes, such as a publisher, should be defined in a parent entity like "Publication," while unique attributes should reside in their respective entities, such as "Books" and "Magazines." Additionally, the conversation touches on the challenges of using yUML for diagramming, particularly the inability to combine different geometric shapes from various diagram types.
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What if you have some other entity, such as publication, with books and magazines as subclasses (or subentities)?colt said:I am doing a project of an entity relationship model and a doubt came: Should repeated attributes of the entities be shared? Or I must reproduce these to every entity? In another words, if two of my entities are books and magazines, shall I have a single publisher attribute, or one for each?
Mark44 said:What if you have some other entity, such as publication, with books and magazines as subclasses (or subentities)?
Whatever attributes that both books and magazines have in common could be defined in the publication entity, and the attributes that books and magazines don't share would go in one or the other of these entities.
That's just my take...