Can you explain a bit how you derived it?

The Gateway to Computer Science Excellence

+4 votes

+4

Given R(A1,A2,A3,A4,A5 )

Now by seeing FD , you can derive A2,A5,A1 ... so remaining attribute should also be in candidate key ...

So A3A4 must be in ck .. but

A3A4 + (closure of A3A4) = A3A4 , only so its not candidate key bcoz it does not derive all attribute of relation

now Consider A3A4A1 +(closure of A1A3A4)= A3,A4,A1,A2,A5 SO IT derive all attribute of relation

similar A3A4A2 and A3A4A5 also derive all attribute ...

Now by seeing FD , you can derive A2,A5,A1 ... so remaining attribute should also be in candidate key ...

So A3A4 must be in ck .. but

A3A4 + (closure of A3A4) = A3A4 , only so its not candidate key bcoz it does not derive all attribute of relation

now Consider A3A4A1 +(closure of A1A3A4)= A3,A4,A1,A2,A5 SO IT derive all attribute of relation

similar A3A4A2 and A3A4A5 also derive all attribute ...

- All categories
- General Aptitude 1.9k
- Engineering Mathematics 7.5k
- Digital Logic 2.9k
- Programming and DS 4.9k
- Algorithms 4.4k
- Theory of Computation 6.2k
- Compiler Design 2.1k
- Databases 4.1k
- CO and Architecture 3.4k
- Computer Networks 4.2k
- Non GATE 1.4k
- Others 1.4k
- Admissions 595
- Exam Queries 573
- Tier 1 Placement Questions 23
- Job Queries 72
- Projects 18

50,737 questions

57,321 answers

198,399 comments

105,151 users