To prepare for my exam I have completed many exercises. Most of them were solvable without any problems. But the following task I could not solve until now. It is:
You are given the relation scheme
R (A,B,C,D)with the three functional dependencies:
AB → C
C → D
D → A
In which normal form is
R(1st, 2nd or 3rd)? Justify your statement.
Could anyone of you please help me? A good explanation and substantiation would be very, very good!
Thank you sooo much!
P.S.: I already have one solution from a friend. But I do not know if it is correct…
He said that it is the second normal form because the non-key attributes
D are fully functional depending on
A, B. Besides he mentioned that it is not the third normal form because there is a transitive dependence between the non-key attributes (
A, B → C and
C → D).