Q. 64 Consider the following four relational schemas. For each schema, all non-trivial functional dependencies are listed, The underlined attributes are the respective primary keys.
- Schema I: Registration(rollno, courses)
Field ‘courses’ is a set-valued attribute containing the set of courses a student has registered for.
Non-trivial functional dependency
rollno → courses - Schema II: Registration (rollno, coursid, email)
Non-trivial functional dependencies:
rollno, courseid → email
email → rollno - Schema III: Registration (rollno, courseid, marks, grade)
Non-trivial functional dependencies:
rollno, courseid, → marks, grade
marks → grade - Schema IV: Registration (rollno, courseid, credit)
Non-trivial functional dependencies:
rollno, courseid → credit
courseid → credit
Which one of the relational schemas above is in 3NF but not in BCNF?
(A) Schema I
(B) Schema II
(C) Schema III
(D) Schema IV
Answer: (B)
Explanation:
