Question

Consider the following relational schema and set of functional dependencies.

S(A,B,C,D,E,F,G)

D → E

E → B

C → FG

BE → AC

Is the decomposition of S into S1(E,G,F) and S2(A,B,C,D,G) a lossless join decomposition?

Choose one of the following queries as your answer: SELECT ’lossy’; SELECT ’lossless’;

Answer 1

consider the following relational schema and set of functional dependencies

  S(A,B,C,D,E,F,G,)

D E

E B

C FG

BE AC

First identify key in above relation

in above relation 'D' is a Primary key

Below picture clearly explain the lossless Decomposition

Choose one of the following quries as your answer :SELECT 'lossy'; SELECT 'lossless'

Im writing Both Quries

1 .SELECT 'lossy' Qurie

solution: SELECT *FROM S1 INNERJOIN S2 ON S1.G= S2.G

Explonation qurie: this Qurie represents only S1 and S2 Contains common Elements prints So this Qurie is lossy Qurie

2.SELECT 'lossless' Qurie

solution: SELECT * FROM S1 FULLOUTERJOIN S2 WHERE S1.G =S2.G

Eplonation qurie: this Qurie represents all elements in Both Relations So no lossy the Data this is know as lossless

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