Soru
3. Suppose we decompose R given in question 1 into R_(1)=(A,B,C) and R_(2)=(A,D,E) show that this decomposition is lossless join decomposition if the functional dependencies in set F given in question 1 hold. F= A-gt BC,CD-gt E,B-gt D,E-gt A 4. Give a lossless join decomposition into BCNF of schema R under given in question 1. F= Aarrow BC,CDarrow gt ,,arrow arrow D,Earrow A
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Kıdemli · 11 yıl öğretmeni
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3. To show that the decomposition of R into
and
is a lossless join that the join of
and
on the common attribute A is equal to the original relation R, and that there is no loss of information in the decomposition.Given the functional dependencies in set F:
We can see that the attribute A in
and
is a common attribute, and it determines the attributes B, C, and E in
, and the attribute D in
. Therefore, when we join
and
on the attribute A, we will get the original relation R without any loss of information.Thus, the into
and
is a lossless join decomposition.4. To give a lossless join decomposition of schema R into BCNF, we need to decompose R into relations where each relation is in BCNF, and the join of these relations is equal to the original relation R.Given the functional dependencies in set F:
We can see that the attribute A in
and
is a common attribute, and it determines the attributes B, C, and E in
, and the attribute D in
. Therefore, we can decompose R into two relations
R_{2}=(A,D,E)
R_{1}=(A,B,C)
R_{1}
R_{2}=(A,D,E)
R_{2}
R_{1}=(A,B,C)
R_{2}=(A,D,E)$.