Second Normal Form (2NF)


Second Normal Form builds on First Normal Form.

A table must already be in 1NF to move to 2NF.

2NF removes partial dependency.

Partial dependency occurs when a column depends on part of a composite primary key.

This causes data redundancy.

If a table has a composite key, all non-key columns must depend on the full key.

Otherwise the table is not in 2NF.

In this table, student_name depends only on student_id and course_name depends only on course_id.

This violates Second Normal Form.

Second Normal Form removes partial dependency.

It separates data into logical tables.

2NF improves data consistency.