Recall that a relation R is in BCNF, if for every Functional Dependency (FD) of the form A1 …An -> B, the determinant { A1 …An} is a candidate key (or a superkey) for R.
Consider the following relation and sets of FDs:
R(A,B,C,D) with FDs:
1. AB -> C
2. BC -> D
3. CD -> A
4. AD -> B
Assume these FDs capture all we know about the attributes of R.
i) Find all the keys in R. (2 marks).
ii) Indicate all BCNF violations. (2 marks).
iii) Given these violations:
a) Suggest two different decompositions of R, that are in BCNF. (4 marks).
b) Show additionally that the following decomposition
R1(A,B,C), R2(A,B,D)
is in BCNF. (2 marks).
Hint for i): start by looking for one-attribute keys, then 2-attribute keys, etc.
Am slighlty confuse with these questions, if would be great if someone could kindly explain it to me as Normalisation baffles me. Cheers :D
