Project ForgeSign up free
Database Management Systems
Normalization
GATE 2016
Easy

Which of the following is NOT a superkey in a relational schema with attributes V, W, X, Y, Z and primary key VY?

  • AVXYZ
  • VWXZ
  • CVWXY
  • DVWXYZ

Explanation

A superkey must contain every attribute of at least one candidate key — here, both V and Y (the primary key VY). VXYZ, VWXY, and VWXYZ all contain both V and Y, so they're superkeys. VWXZ is missing Y entirely, so it cannot functionally determine the whole relation and is NOT a superkey.

Source: GATE CS 2016 (Session 1 / Set A) (2016)

This question is part of a 15-day revision cycle — sign in and Project Forge will bring it back the day before you'd forget it.

Start revising free