Question

Suppose that I have a relation with the following structure, where (EmployeeID, Department) is a composite primary key.

DEPARTMENT (EmployeeID, EmployeeName, Department, TotalSales).

Further suppose that the following functional dependencies exist

(EmployeeID, Department) → (EmployeeName, TotalSales)

EmployeeID → EmployeeName

True or False: The above relation is in 2NF.

True or False: A relation in second normal form is automatically in third normal form.

True or False: If PartNumber → PartWeight, then PartNumber will be unique in a relation.

Answer 1

A. The relation is in 2NF.

This is False because the relation contains partial functional dependency EmployeeID -> EmployeeName .

This is partial functional dependency since EmployeeID is primary key attribute. And partial functional dependency violates 2NF.

Therefore the given relation is not in 2NF.

B. A relation in second normal form is automatically in third normal form.

This is False.

When a relation is in 2NF, it still can contain transitive functional dependency. And transitive functional dependency violates 3NF

So the given statement is False.

When a relation is in 3NF , then it automatically is in 2NF.

C. If PartNumber → PartWeight, then PartNumber will be unique in a relation.

False.

PartNumber will be unique in a relation only if PartNumber is primary key for the relation. What if, partNumber -> partWeight is a transitive functional dependency. Then PartNumber can contain duplicate value.

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