Which of the following is not true about subtype entities?
A)Subtypes may be exclusive.
B)The supertype and subtypes will have the same identifier.
C)Subtypes are used to avoid a situation in which some attributes are required to be null.
D)All subtypes of a supertype must have the same attributes.

Question

Quizplus · Accepted Answer

Option D is not entirely true about subtype entities. Subtypes of a supertype may have different attributes, though they must possess at least one unique attribute. Therefore, option D is not true, and the others are correct. Option A says that subtypes may be exclusive; option B says that the supertype and subtypes have the same identifier or primary key attribute in the ER diagram, and option C states that subtypes are used to avoid a situation where some attributes are required to be null. All these statements are true about subtype entities.

Which of the Following Is Not True About Subtype Entities