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Database MCQ - Database design

16:  

 Which-one ofthe following statements about normal forms is FALSE?

A.

BCNF is stricter than 3 NF

B.

Lossless, dependency -preserving decomposition into 3 NF is always possible

C.

Loss less, dependency - preserving decomposition into BCNF is always possible

D.

Any relation with two attributes is BCNF

 
 

Option: C

Explanation :

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17:  

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?

A.

AE, BE

B.

AE, BE, DE

C.

AEH, BEH, BCH

D.

AEH, BEH, DEH

 
 

Option: D

Explanation :

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18:  

The following functional dependcies are given:
AB -> CD, AF —> D, DE --> F, C —> G, F —› E, G --> A
Which one of the following options is false?

A.

{CF}+ = {ACDEFG}

B.

{BG}± = {ABCDG}

C.

{AE }+ = {ACDEFG}

D.

{AC = {ACDFG}

 
 

Option: C

Explanation :

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19:  

 Which one ofthe following statements is FALSE?

A.

Any relation with two attributes is in BCNF

B.

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

C.

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

D.

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

 
 

Option: D

Explanation :

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20:  

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 dependecies:
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 ofthe following statements is true?

A.

Both Book and collection are in BCNF

B.

Both Book and collection are in 3NF only

C.

Book is in 2NF and Collection is in 3NF

D.

Both Book and Collection are in 2NF only

 
 

Option: C

Explanation :

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