Advanced Database Management System - Tutorials and Notes: Which of the normal form does the given relation satisfy

Search Engine

Please visit, subscribe and share 10 Minutes Lectures in Computer Science

Thursday, 6 October 2016

Which of the normal form does the given relation satisfy

Find the normal form of the given relation schema / Which of the normal form does the given relation satisfy? / The relational table is in 2NF, 3NF or BCNF?


Question:


4. Assume a relation R with the schema R(A, B, C, D, E) and a set F of functional dependencies as follows; F = {A → B, C → D, D → E} The relation R is not in Second Normal Form (2NF). Why?

(a) R has no repeating groups
(b) R has transitive functional dependencies
(c) R has partial functional dependencies
(d) R has no key



Answer:

(c) R has partial functional dependencies


As per the question,

  • Given - Schema of relation R and the set F of functional dependencies.
  • Not known - The key.
The key for R is AC, a composite key (combination of two or more attributes). When we have composite keys, we need to verify that all the non-key attributes are fully functionally dependent on the whole key or not. In our question, the non-key attributes are B, D, and E. B is fully functionally dependent on A alone (A is part of AC, and B is partially dependent on AC), D is fully functionally dependent on C alone (C is part of AC, and D is partially dependent on AC). Hence, the rule for 2NF is violated and R is not in 2NF.








         Previous Question                                                                                Next Question


No comments:

Post a comment

Featured Content

Multiple choice questions in Natural Language Processing Home

MCQ in Natural Language Processing, Quiz questions with answers in NLP, Top interview questions in NLP with answers Multiple Choice Que...

All time most popular contents