GATE Overflow Test Series | Databases | Test 1 | Question: 4

Question

Which of the following is/are correct regarding a weak entity in Entity-Relationship model? (Mark all the appropriate options)

• A. Every weak entity has to be related to a strong entity through a strong relationship
• B. A weak entity cannot be uniquely identified by its own attributes
• C. The participation of weak entity in its identifying relationship is total
• D. A weak or non-identifying relationship exists between two entities when the primary key of one of the related entities contain a primary key component of the other related entities

Comments

@gatecse What is strong relationship in Option A? Shouldn’t it be identifying relationship?

---

@Ayan Kumar Pahari identifying relationship is also called a strong relationship.

---

@rana11shubham noted thanks.

Answer 1

Options A, B, and C are true for a weak entity. It is existentially dependent on a strong entity and so its relationship with that entity must be total.

Option D is false.  A weak or non-identifying relationship exists between two entities when the primary key of one of the related entities does not contain a primary key component of the other related entities. A strong or identifying relationship is when the primary key of the related entity contains the primary key of the “parent”

So, correct options: A, B, C.

Reference: https://www.cs.dartmouth.edu/~cs61/Lectures/04%20-%20ER%20Modeling/04%20-%20ER%20Modeling.html

Comments

Isn’t this statement false-
 

1. Every weak entity has to be related to a strong entity through a strong relationship.
   
   There are related with Week Relationship...only B,C should be the answer

---

Sir, Kindly clear this doubt about the weak and strong relationship.

---

every ?