Question

Does Boyce-Codd normal form require the 3rd normal form to begin with?
True or False

Answer 1

Boyce-Codd Normal Form (BCNF) does not require the 3rd Normal Form (3NF) to begin with. BCNF is a higher level of normalization that focuses on eliminating certain kinds of functional dependencies. A relation satisfying BCNF is automatically in 3NF.

Step-by-step explanation:

Boyce-Codd Normal Form (BCNF)

Boyce-Codd Normal Form (BCNF) is a higher level of normalization in database design. It is stricter than the 3rd Normal Form (3NF) in terms of eliminating redundancy and ensuring dependencies are preserved.

Relation to 3rd Normal Form (3NF)

BCNF does not require a relation to be in 3NF to begin with. Instead, it focuses on eliminating certain kinds of functional dependencies known as non-trivial functional dependencies. A relation that satisfies BCNF is automatically in 3NF.

Example

Let's consider the following relation:

• Employee(EmployeeId, EmployeeName, DepartmentId, DepartmentName)

In this relation, EmployeeId uniquely identifies an employee, and DepartmentId uniquely identifies a department. Both EmployeeName and DepartmentName are functionally dependent on EmployeeId and DepartmentId respectively. However, DepartmentName is also functionally dependent on EmployeeId due to the presence of a transitive dependency. To bring this relation to BCNF, we split it into two relations:

1. Employee(EmployeeId, EmployeeName, DepartmentId)
2. Department(DepartmentId, DepartmentName)