Question

Define Third Normal Form (3NF).

Hint:

To achieve 3NF, first ensure the table is in 2NF, then eliminate transitive dependencies among non-prime attributes.

Answer 1

Step 1: Understanding Third Normal Form.
Third Normal Form (3NF) is a property of a relational database that ensures that a database is free of transitive dependencies. A relation is in 3NF if it is in Second Normal Form (2NF) and if no non-prime attribute (an attribute that is not part of any candidate key) is transitively dependent on the primary key.
Step 2: Example of 3NF.
To ensure a database is in 3NF, any non-prime attribute must depend only on the primary key and not on other non-prime attributes. For instance, if a table contains attributes such as Student ID, Student Name, and Department, where Student Name depends on Student ID, but Department depends on Student Name, this would violate 3NF. The table would need to be reorganized.
Step 3: Conclusion.
The main goal of 3NF is to eliminate redundancy and ensure that attributes only depend on the primary key.