What is Boyce-Codd Normal Form?

Explain Boyce-Codd Normal Form.

A relation is in BCNF if and only if every determinent is a candidate key. It is stronger form of normalization than 3NF because it eliminates the second condition for 3NF, which allows the right side of the functional dependency to be a prime attribute. So we can define it as, A relation is in BCNF if and only if every determinant is a candidate key.

Example: Let us consider a relation TEACHING which has three attributes: Student, Course, and instructor. TEACHING (Student, Course, Instructor). In this relation, Student determines the course which determines the instructor. Also instructor determines the course which he has to handle. If an instructor is having a command in a particular subject, naturally he would like to handle the subject or course. The relation TEACHING can be transformed into BCNF by splitting the relation into two relations R1 and R2. R1(Instructor, Course) and R2 (Instructor, Student). By splitting the relation TEACHING into two relations R1 and R2 we have transformed the relation TEACHING into BCNF because for the relation to be in BCNF all nonprime attributes must be fully dependent on every key. In the relation R1, the nonprime attribute course is fully dependent on the key attribute Instructor.