Exercise 12: Identifying Normal Forms

Armstrong’s Axioms and rules for splitting and combining.

Consider the relation R(A,B,C,D). For each of the following sets of FDs,

  1. C → D, C → A, B → C
  2. B → C, D → A
  3. ABC → D, D → A
  4. A → B, BC → D, A → C
  5. AB → C, AB → D, C → A, D → B

assuming those are the only dependencies that hold for R, do the following:

a) Identify the candidate key(s) for R.

b) Identify the best normal form (3NF or BCNF) that R satisfies.

c) If R is not in BCNF, decompose it into a set of BCNF relations.