Third+Normal+Form

**Introduction**

The final step is to produce the data in Third Normal Form (3NF). Third Normal Form removes any attributes which depend on non-key columns in the table. This is known as removing transitive dependencies.

1. Identify any dependencies between non-key attributes within each table 2. Remove them to a new table 3. Decide on a primary key 4. This primary key becomes the foreign key in the original table

**Example**

Working with our courses entity from Second Normal Form...



...f ollow the steps to show the data in Third Normal Form (3NF)


 * 1. Identify any dependencies between non-key attributes **

In the table **course, teacher_name** is dependent on **teacher_id**. These means that at present the teacher name will be repeated for every course that they teach.


 * 2. Remove these dependencies between non-key attributes to a new table, and decide on a primary key **