schema R = (A,B,C,D,E) and the set F of functional dependencies: A ->B C ->D BD

Question

schema R = (A,B,C,D,E) and the set F of functional dependencies:

A ->B

C ->D

BD -> E

1. Which of the following properties apply to the set of schemas (A,B), (C,D), (B,D,E)?

(a) 3NF

(b) BCNF

(c) lossless

(d) dependency preserving

(e) not a decomposition of R

2. Which of the following properties apply to the set of schemas (A,B), (C,D), (A,C,E)?

(a) 3NF

(b) BCNF

(c) lossless

(d) dependency preserving

(e) not a decomposition of R

3. Which of the following properties apply to the set of schemas (A,B), (C,D), (B,D,E), (A,C)?

(a) 3NF

(b) BCNF

(c) lossless

(d) dependency preserving

(e) not a decomposition of R

Explanation / Answer

1) d) dependency preserving

A,B), A->B

(C,D), C-> D

(B,D,E) BD -> E

SO ALL THE THREE DEPENDENCIES ARE USED IN DECOMPOSED TABLES SO DEPENDENCIES ARE PRESERVED

2) a) 3NF

dependency ARE NOT preserved so 3NF

3) (c) lossless

(A,B), (C,D), (B,D,E), (A,C) BY TAKING UNION WE CAN OBTAIN PARENT TABLE WITHOUT LOSING ANY FIELD

Related Questions

Navigate

• Browse (All)
• Browse S
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.