So for my database project, I designed a meat supply chain optimization project for a large organization, for example such as walmart, where every part of the chain is owned by the organization, (transport, farm, retail store etc). I created an entity called Workplace with primary attribute Workplace_ID, and other attributes Type (farm, retail store, transport etc) and location. Workplace_ID is also the primary key for the other workplaces such as Slaugherhouse, Farm, Transport etc. What I intended was to do was for the other entities’ primary key to be foreign key Workplace_ID, where I could easily create new tables specifying type and workplace_ID, relating Workplace entity to for example Farm entity. I have linked the ERD diagram here so that you can see how it was designed.
The problem was, my professor didn’t even listen to my final presentation, he just saw the auto generated ERD from XAMPP, and said that we were kidding him and wasting his time with a single attribute entity (Farm) having a foreign key as primary key, with the relation being 1 to 1. He then asked us to provide one example from anywhere of such a thing existing, an ERD would serve as a valid example, implying that such a thing was impossible to find, with the implication being if we could not provide any example we would receive 0.
An important thing to note that he did not let me clarify my design choices, and that I intended it to be a IS A 1-1 relationship, sure, as in one instance of farm entity can only be one instance of workplace entity, but also that not all instances of workplace entities were instances of farm entities, it would only be instances of workplace entities which had farm as the type attribute. I designed it as such so that all workplaces did not have to include their locations and types again and again in their attributes, you would create a relationship table between two entities specifying type and Workplace_ID. I designed it in such a way since for some, Workplace_ID is primary key, whereas for others, it is simply a foreign key relating to other entities (for example, Batch has Workplace_ID signifying where the particular batch came from (which slaughterhouse), but its primary key is Batch_ID).
Could Someone please point me to any example or cite something to potentially even save my grade?
The deadline for coming up with even a single example is before my final exam, on the 30th of September. Thanks for taking the time to read, and sorry for this bother.