Question
Download Solution PDFConsider the schema R = (A, B, C, D, E, F) on which the following functional dependencies hold:
A ➝ B
B, C ➝ D
E ➝ C
D ➝ A
What are the candidate keys of R?Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFConcept:
Candidate key: it is the set of attributes which uniquely identifies a relation. It is also known as superkey with no repeated attributes.
Explanation:
Given relation R = {A, B, C, D, E}
A ➝ B
B, C ➝ D
E ➝ C
D ➝ A
Find the closure of keys given. If all the attributes of relation are present in the closure, then it will be the candidate key of that relation.
Option1: AEF, BEF and DEF
(AEF)+ = {A, E, F, B, C, D}
(BEF)+ = {B, E, F, C, D, A}
(DEF)+ = {D, E, F, C, A, B}
These are the candidate keys of given relation.
Option2: AEF, BEF and BCF
(AEF)+ = {A, E, F, B, C, D}
(BEF)+ = {B, E, F, C, D, A}
(BCF)+ = {B, C, F, D, A} / E is not present in the closure. Not the candidate key
Option3: AE and BE
(AE)+ = {A, E, C, B, D, } /F is not present, not a candidate key
(BE)+ = {B, E, C, D, A} /F is not present, not a candidate key
Option4: AE, BE and DE
(AE)+ = {A, E, C, B, D, } /F is not present, not a candidate key
(BE)+ = {B, E, C, D, A} /F is not present, not a candidate key
(DE)+ = {D, E, A, C, B} /F is not present, not a candidate key
Last updated on Jun 11, 2025
-> The UGC NET Exam Schedule 2025 for June has been released on its official website.
-> Check UPSC Prelims Result 2025, UPSC IFS Result 2025, UPSC Prelims Cutoff 2025, UPSC Prelims Result 2025 Name Wise & Rollno. Wise
-> The UGC NET Application Correction Window 2025 is available from 14th May to 15th May 2025.
-> The UGC NET 2025 online application form submission closed on 12th May 2025.
-> The June 2025 Exam will be conducted from 21st June to 30th June 2025
-> The UGC-NET exam takes place for 85 subjects, to determine the eligibility for 'Junior Research Fellowship’ and ‘Assistant Professor’ posts, as well as for PhD. admissions.
-> The exam is conducted bi-annually - in June and December cycles.
-> The exam comprises two papers - Paper I and Paper II. Paper I consists of 50 questions and Paper II consists of 100 questions.
-> The candidates who are preparing for the exam can check the UGC NET Previous Year Papers and UGC NET Test Series to boost their preparations.