Database - Data Modeling with ER Model - Discussion

Discussion :: Data Modeling with ER Model - General Questions (Q.No.2)

2. 

Which type of entity cannot exist in the database unless another type of entity also exists in the database, but does not require that the identifier of that other entity be included as part of its own identifier?

[A]. Weak entity
[B]. Strong entity
[C]. ID-dependent entity
[D]. ID- independent entity

Answer: Option A

Explanation:

No answer description available for this question.

Rahul said: (Nov 19, 2011)  
Weak entity is fully dependent on the strong entity and denoted by doubly ractangle underlined.

Shivang Gupta said: (Jan 28, 2014)  
See here it is mentioned that it "does not require that the identifier of that other entity be included as part of its own identifier?".

So how can weak entity type be the answer as it requires the primary key of the strong entity type which is in relation to it via identifying relationship type. Please explain me. :).

Yogesh said: (Dec 6, 2015)  
WEAK ENTITY - An entity that cannot exist in a database unless another type of entity also exists in that database.

Pankaj Das said: (May 28, 2016)  
I am also bit confused, and how could the answer be WEAK ENTITY?

To be a weak entity, this is also required that the primary key of the weak entity should use the key of the table, on which it depends for existence.

Muditha said: (Jun 10, 2016)  
A weak entity can have a partial key but it doesn't uniquely identify it, so it needs the primary key of its strong entity too.

Kishore Pola said: (Sep 13, 2017)  
@Shivang Guptha and @Pankaj Das:

As in question given that the strong entity does not req that the identifier of that other entity be included as part of its own identifier? so, if strong entity itself does not requiring the stuff in weak entity with his identifier so, how could it exit?

Mohammed said: (Jan 9, 2018)  
Thank you for the given explanation.

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