Database - Data Modeling with ER Model - Discussion

Discussion :: Data Modeling with ER Model - General Questions (Q.No.4)


Which type of entity represents an actual occurrence of an associated generalized entity?

[A]. Supertype entity
[B]. Subtype entity
[C]. Archetype entity
[D]. Instance entity

Answer: Option D


No answer description available for this question.

Harshit said: (May 24, 2011)  
Can somebody elaborate this answer ?

Prince Singh said: (Jan 19, 2012)  
Can someone explain this answer?

David said: (Apr 19, 2013)  
What is an instance entity?

Jiten said: (Aug 2, 2013)  
It might help to think of an entity as a thing.

So you are asking about a type of thing, and an actual instance of that thing.

For example, one type of thing is a Person. Brad Pitt is an instance of a Person. A Fruit is a type of thing, and an Apple is an instance of a Fruit.

Make sense?

In a database world you might name a table after the type of an entity, like a Car. However, each record in the table is an instance of a Car, like Ford Mustang.

Sonal said: (Mar 2, 2016)  
Can someone elaborate the types of entities that are given in the question?

Pankaj Das said: (May 28, 2016)  

Subtype will also correct. If PERSON is a generalized entity, then EMPLOYEE, STUDENT these are subtype entity.

How did you explain here? It seems the subtype and instance entity both is synonymous.

But, as we have both the option in the question, it caused the confusion.

Debanjan Dey said: (Aug 13, 2016)  
Suppose Brad Pitt is an instance of a person. He may or may not be an employee or a student but a person indeed. So we choose the instance.

Selvam said: (Jan 4, 2018)  
Can someone explain it please?

Yogeetha said: (Apr 27, 2020)  
Now, It's clear. Thanks @Jiten @Debanjan Dey.

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