GATE 2015 CS (CS3) – Question 13

Databases · Integrity Constraints and Normal Forms · 1 mark · Multiple choice

For X(P,Q,R,S,T,U), F={PR→ST, PSU→QR}. Which dependency in F⁺ is trivial?

PR→ST
PR→RT
PS→S
PSU→Q

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (C) PS→S

Explanation

A functional dependency A→B is trivial precisely when B is a subset of A. Only PS→S has its right side contained in its left side. It follows by reflexivity regardless of the supplied nontrivial dependencies. Thus C.

More Integrity Constraints and Normal Forms questions

GATE 2021 CS (CS2) Q50 – On U(P,Q,R,S,T), dependencies P→QR and RS→T hold. Which can be inferred?
GATE 2026 CS (CS1) Q31 – In the context of relational database normalization, which of the following statements…
GATE 2026 CS (CS1) Q65 – Consider a relational database schema with a relation R(A, B, C, D). If \A, B\ and \A, C\…
GATE 2026 CS (CS2) Q42 – In the context of schema normalization in relational DBMS, consider a set F of functional…
GATE 2025 CS (CS2) Q46 – Consider the following relational schema along with all the functional dependencies that…
GATE 2024 CS (CS1) Q22 – Which of the following statements about a relation R in first normal form (1NF) is/are…

All Integrity Constraints and Normal Forms questions →