Consider a relation scheme R = (A, B, C, D, E, H) on which the following functional dependencies hold: {A —> B, BC ---> D, E, —> C, D —> Al . What are the candidate keys of R?

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18

Databases MCQ with Answers

18) Consider a relation scheme R = (A, B, C, D, E, H) on which the following functional dependencies hold: {A —> B, BC ---> D, E, —> C, D —> Al . What are the candidate keys of R?

AE, BE

AE, BE, DE

AEH, BEH, BCH

AEH, BEH, DEH

Answer is:

AEH, BEH, DEH

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20) Which one of the following statements is FALSE

Any relation with two attributes is in BCNF

A relation in which every key has only one attributes is in 2NF

A prime attribute can be transitively dependent on a key in 3 NF relation

A prime attribute can be transitively dependent on a key in a BCNF relation

Answer is:

A prime attribute can be transitively dependent on a key in a BCNF relation

21) Consider the following relational schemes for a library for a library database:
Book (Title, Author, Catalog_no, Publisher, Year, Price)
Collection (Title, Author, Catalog_no)
Which ofthe following functional dependencies:
I. Title Author —› Catalog no.
II. Catalog_no ---> Title Author Publisher Year
III. Publisher Title Year --> Price.
Assume {Author, Title) is the key for both schemes: Which of the following statements is true?

Both Book and collection are in BCNF

Both Book and collection are in 3NF only

Book is in 2NF and Collection is in 3NF

Both Book and Collection are in 2NF only

Answer is:

Book is in 2NF and Collection is in 3NF

22) Manager's salary details are hidden from the employee. This is

conceptual level data hiding

physical level data hiding

external level data hiding

none of these

Answer is:

conceptual level data hiding

23) The employee salary should not be greater than Rs. 2000. This is

integrity constraint

referential constraint

over-defined constraint

feasible constraint

Answer is:

integrity constraint

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18) Consider a relation scheme R = (A, B, C, D, E, H) on which the following functional dependencies hold: {A —> B, BC ---> D, E, —> C, D —> Al . What are the candidate keys of R?

AEH, BEH, DEH

Databases MCQ with Answers

Related Databases MCQ with Answers

20) Which one of the following statements is FALSE

A prime attribute can be transitively dependent on a key in a BCNF relation

Book is in 2NF and Collection is in 3NF

22) Manager's salary details are hidden from the employee. This is

conceptual level data hiding

23) The employee salary should not be greater than Rs. 2000. This is

integrity constraint

Databases MCQ with Answers