INF2603 Assignment 5 (865742) 2025 (Comprehensive Response) Due 5 September 2025

INF2603
Assignment 5
Unique No: 865742
Due 5 September 2025

, INF2603 Assignment 5 (865742) Due 5 September 2025


Database Design and SQL


1. Situations When a 3NF Relation is in BCNF and When It Is Not

3NF Relation is Also in BCNF


A relation in 3NF is also in BCNF if every functional dependency (FD)
has a candidate key as its determinant.
This eliminates all redundancy.


Example:

STUDENT(StudentID → Name, StudentID → Email)


Candidate key: StudentID



All FDs have StudentID on LHS → satisfies 3NF and BCNF.


3NF Relation Not in BCNF

A relation may be in 3NF but not in BCNF if a non-key attribute is a
determinant.

Example:

COURSE(CourseID, Lecturer, Room)
FD: Lecturer → Room


Primary key: CourseID

Relation satisfies 3NF (no transitive dependency),

But violates BCNF since Lecturer is not a candidate key.