Consider the relation: BOOK (Book, Author, Edition, Year) ----------------------
ID: 3817811 • Letter: C
Question
Consider the relation:
BOOK (Book, Author, Edition, Year)
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Book Author Edition Year
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DB_fundamentals Navathe 1 1990
DB_fundamentals Elmasri 1 1990
DB_fundamentals Elmasri 7 2015
DB_fundamentals Navathe 7 2015
Database Silberschatz 1 2015
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(a) (2) Does the above instance have one or more functional dependencies? If so, what are the FDs?
(b) (2) What are the candidate keys?
(c) (3) Decompose into BCNF relations.
(d) (3) Does the original BOOK relation instance have non trivial MVDs? If so, what are the MVDs?
Explanation / Answer
Answer:
Book Author Edition Year
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DB_fundamentals Navathe 1 1990
DB_fundamentals Elmasri 1 1990
DB_fundamentals Elmasri 7 2015
DB_fundamentals Navathe 7 2015
Database Silberschatz 1 2015
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(a) (2) Does the above instance have one or more functional dependencies? If so, what are the FDs?
Based on the data available in the table, there is only one FD
Book, Author, Edition -> Year
(b) (2) What are the candidate keys?
As By combining Book, Author and Edition we can retrive all the columns of the table so there
Candidate Key:{(Book, Author, Edition)}
(c) (3) Decompose into BCNF relations.
There is no any non-trivial FDs, and all the determinant in available FDs are candidate key therefore this relation is in BCNF.
(d) (3) Does the original BOOK relation instance have non trivial MVDs? If so, what are the MVDs?
Original BOOK relation instance does not have any non trivial MVDs