Database-Management-System

Question 9

Which one of the following is used to represent the supporting many-one relationships of a weak entity set in an entity-relationship diagram?

A	Ovals that contain underlined identifiers
B	Rectangles with double/bold border
C	Diamonds with double/bold border
D	Ovals with double/bold border

Database-Management-SystemER-ModelGATE 2020Video-Explanation

Question 9 Explanation:

An entity set that does not have sufficient attributes to form a primary key is termed as a weak entity and an entity set that has a primary key is termed as strong entity set. For a weak entity set to be meaningful, it must be associated with another entity set, called identifying or owner entity set. The relationship associating the weak entity set with the identifying entity set is called the identifying relationship and it is represented by double diamond. The identifying relationship is many-to-one from the weak entity set to the identifying entity set and the participation of weak entity set in the relationship is total.

Correct Answer: C

Question 9 Explanation:

An entity set that does not have sufficient attributes to form a primary key is termed as a weak entity and an entity set that has a primary key is termed as strong entity set. For a weak entity set to be meaningful, it must be associated with another entity set, called identifying or owner entity set. The relationship associating the weak entity set with the identifying entity set is called the identifying relationship and it is represented by double diamond. The identifying relationship is many-to-one from the weak entity set to the identifying entity set and the participation of weak entity set in the relationship is total.