Monday 8 June 2020

5. PGT Computer Science Question Discussion



Which one of the following statements is False?
(A) Any relation with two attributes is in BCNF
(B) A relation is which every key has only one attribute is in 2NF
(C) A prime attribute can be transitively dependent on a key in 3NF
(D) A prime attribute can be transitively dependent on a key in BCNF

option (A) is correct: A relation with only two attributes always in BCNF bcoz an attribute must be primary key so there will be no chance of non-key attribute in left side

option(B) is correct: bcoz if every key has only only attribute then there will be no chance for subpart of key so there never be a partial dependency

option(C) is correct: bcoz according to definition of 3NF

3 NF – A relation R is in third normal form (3NF) if and only if it is in 2NF and every non-key attribute is non-transitively dependent on the primary key.
means non prime can not be dependent on prime, but not key or non prime attributes
but prime attributes can be dependent on prime, but not key or non prime

option(D) is worng: bcoz according to BCNF on left side there will be always a Key or super key.
So no attribute can be transitively dependent on a key

So the correct answer is Option (D) 

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