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Course Content

Relational Database and Normalization

Third Normal FormThird Normal Form

The Third Normal Form rules:

  • Requires the Second Normal Form.
  • All attributes that do not belong to the primary key, but belong to another attribute, should be placed in a separate table.

There are moments when you want to append a new attribute in the table, but sometimes it will expand the table to an incredible size! And if the attributes are not tied to the main key - this is illogical!

Look at an example:

Here, Designer Grade and Designer Country are not Project's attributes. These attributes are tied to Designer only.

Let's normalize it!

Cool! Now we have two entities with separate tables:

  • Project has only its attributes.
  • Designer has only his attributes.

Results: Third Normal Form


Advantages
Improves the structure of the database
Takes up less memory

question-icon

What mean the Third Normal Form?

Select a few correct answers

Section 3.

Chapter 4