Consider the following four relational schemas. For each schema, all non-trivial functional dependencies are listed
Q. 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, courseid, 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
Ans: Schema II