Made Easy Mock

Question

Consider the following statements about relation R:

S1: If a relation R is in 3NF but not in BCNF, then relation R must consist proper subset of candidate key determines proper subset of some other candidate key.

S2: If a relation R is in 3NF but not BCNF, then relation R must consist atleast two over-lapped candidate keys.

Which of the following statements is/are correct?

(a) Both S1 and S2

(b) Only S1

© Only S2

(d) None of the above

Comments

this is one example, but  in the S2 they have mentioned that it must have overlapped candidate keys. which i felt it need not be true because we can have so many example proving the S2 AS wrong.

eg:  R(ABCD)

AB->CD, C->B

in the given relation we don't need any overlapped keys but it is in 3NF but NOT IN BCNF.

correct me , if my approach towards the question is wrong.

---

@ajay10 in your example we do have overlapped candidate keys those are $AB, AC$ where A is an overlapped prime attribute.

---

thank you !  i got it ,i didn't overlook it carefully