UGC NET CSE | December 2008 | Part 2 | Question: 30

Question

An entity has:

(i) a set of properties

(ii) a set of properties and values for all the properties

(iii) a set of properties and the values for some set of properties may non-uniquely identify an entity

(iv) a set of properties and the values for some set of properties may uniquely identify an entity

Which of the above are valid?

• A. (i) only        
• B. (ii) only                   
• C. (iii) only        
• D. (iv) only

Answer 1

Option D is the correct answer.

Answer 2

Ans: D

ref: https://books.google.co.in/books?id=SELyJ4a5nTcC&pg=SA2-PA1&lpg=SA2-PA1&dq=An+entity+has+a+set+of+properties+and+the+values+for+some+set+of+properties+may+uniquely+identify+an+entity&source=bl&ots=cZiC_HdafA&sig=r2t3aZyoCJbCnuF0VnWzMWx6GlM&hl=en&sa=X&ved=0ahUKEwiL8ozYpsPWAhWKNI8KHRmhB3QQ6AEIOTAD#v=onepage&q=An%20entity%20has%20a%20set%20of%20properties%20and%20the%20values%20for%20some%20set%20of%20properties%20may%20uniquely%20identify%20an%20entity&f=false

Answer 3

An entity is an object that are represented in the database. For example Mohit, Vasu, CSE306 etc.

An entity is represented or defined by set of attributes. Attributes are the properties used to describe an entity

option D

Answer 4

There two types of entity:

1. Weak Entity (Not Uniquely identified)

2. Strong Entity (Uniquely identified)

So an entity has a set of property and the values for some set of property may uniquely identify an entity.

Option D is correct