Answer to Question #266613 in Databases | SQL | Oracle | MS Access for Prem

Question

Write short notes on the following with suitable examples.

a. 1NF b. 2NF c. 3NF d. BCNF

Answer 1

a.First Normal Form (1NF)

There are no repeated groups in the first normal form since only single values are allowed at the intersection of each row and column. Remove the repeating group and construct two new relations to normalize a relation with a repeating group. For unique identification, the new connection PK is a combination of the previous relation's PK and an attribute from the newly generated relation.

b. Second Normal Form (2NF)

The relation must first be in 1NF for the second normal form. If and only if, the PK contains a single attribute, the relation is automatically in 2NF.

If the connection has a composite PK, each non-key characteristic must be completely reliant on the entire PK, not just a subset of it (i.e., there must be no partial dependency or augmentation).

c. Third Normal Form (3NF)

The relation must be in second normal form to be in third normal form. There must also be no transitive dependencies; a non-key attribute cannot be functionally dependent on another non-key attribute.

d. Boyce-Codd Normal Form (BCNF)

Even though the relation is in 3NF, anomalies can occur when a table has more than one candidate key. 3NF is a specific case of Boyce-Codd normal form. Every determinant must be a candidate key for a relation to be in BCNF.