August 29, 2024
August 29, 2024
August 29, 2024
Database-Management-System
August 29, 2024
 Question 819

A many-to-one relationship exists between entity sets r1 and r2. How will it be represented using functional dependencies if Pk(r) denotes the primary key attribute of relation r?

 A Pk(r1) → Pk(r2) B Pk(r2) → Pk(r1) C Pk(r2) → Pk(r1) and Pk(r1) → Pk(r2) D Pk(r2) → Pk(r1) or Pk(r1) → Pk(r2)
Question 819 Explanation:

Here, we have a many to one relationship between between Set(r1) and Set(r2).

→ Elements of Set(r2) can’t identify elements of Set(r1) because one value element in Set(r2) is pointing to more than one element of Set(r1).
→ So, we can’t say Pk(r2) → Pk(r1) but elements of Set(r1) are pointing to exactly one element of Set(r2) so we can say that Pk(r2) → Pk(r1) because r1 is uniquely identifying r2.
Question 819 Explanation:

Here, we have a many to one relationship between between Set(r1) and Set(r2).

→ Elements of Set(r2) can’t identify elements of Set(r1) because one value element in Set(r2) is pointing to more than one element of Set(r1).
→ So, we can’t say Pk(r2) → Pk(r1) but elements of Set(r1) are pointing to exactly one element of Set(r2) so we can say that Pk(r2) → Pk(r1) because r1 is uniquely identifying r2.