Q.1(Consider schema(R, F), where R=ABCDEF, F={DAC, AE, BED, CDA, A F} a.Find all
ID: 3574969 • Letter: Q
Question
Q.1(Consider schema(R, F), where R=ABCDEF, F={DAC, AE, BED, CDA, A F}
a.Find all the keys of the relation, and for each one, prove it is indeed a key.
b.Decompose the schema into a set of BCNF schemas. Is this decomposition lossless? Is it dependency-preserving? Explain your answer to get full credits.
c.Write an SQL CREATE ASSERTION statement to enforce DAC.
d.What is the minimal cover of F? Describe each step for full credits.
e.Decompose the schema into a set of 3NF schemas. Is this decomposition lossless? Is it dependency-preserving? Explain your answer to get full credits.
Explanation / Answer
a.
Given input functional dependencies: A E; A F; BE D; CD A; D AC.
No input multivalued dependencies.
R0(A, E, F) having FD(s): A E; A F.
R1(D, BE) having FD(s): BE D.
R2(A, CD) having FD(s): CD A.
R3(D, AC) having FD(s): D AC.
Given input functional dependencies: A E; A F; BE D; CD A; D AC.
No input multivalued dependencies.
R0(A, E, F) having FD(s): A E; A F.
R1(D, BE) having FD(s): BE D.
R2(A, CD) having FD(s): CD A.
R3(D, AC) having FD(s): D AC.
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