190k views
0 votes
We have an (over simplified) university database... Decompose into 4NF (and hence BCNF)

(a) What is 4NF?
(b) Identify a non-trivial functional dependency in the given relation.
(c) Explain the concept of BCNF.
(d) How would you decompose the given relation to achieve 4NF?

1 Answer

4 votes

Final answer:

4NF is a database normalization technique that eliminates redundant data and dependencies. Non-trivial functional dependency is when the determinant functionally determines the dependent attribute. BCNF is a higher level of database normalization that ensures no non-trivial dependencies. To achieve 4NF, the given relation would be decomposed by identifying and separating multi-valued dependencies.

Step-by-step explanation:

(a) What is 4NF?

4NF stands for Fourth Normal Form, which is a database normalization technique. It is an extension of third normal form (3NF) and is used to further eliminate redundant data and dependencies. In 4NF, a relation is in 4NF if and only if it is in BCNF (Boyce-Codd Normal Form) and there are no non-trivial multi-valued dependencies.

(b) Identify a non-trivial functional dependency in the given relation.

A non-trivial functional dependency is a dependency where the determinant functionally determines the dependent attribute, and removing any attribute from the determinant would break the dependency. For example, if we have a relation with the attributes Student_ID and Course_ID, where Student_ID uniquely determines Course_ID, this would be a non-trivial functional dependency.

(c) Explain the concept of BCNF.

BCNF stands for Boyce-Codd Normal Form, which is a higher level of database normalization. It deals with functional dependencies and ensures that there are no non-trivial dependencies between attributes. A relation is in BCNF if and only if every non-trivial functional dependency in the relation is a dependency on a candidate key.

(d) How would you decompose the given relation to achieve 4NF?

To decompose the given relation into 4NF, we would first identify all the multi-valued dependencies in the relation. Then, we would create separate relations for each multi-valued dependency. This process is known as normalization and helps in eliminating redundancy and improving data integrity.

User Aldesabido
by
7.6k points
Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.