4.3.0 Database Normal Forms: 1NF, 2NF, 3NF, 4NF and BCNF

Now that we are comfortable with the concepts of decomposition and BCNF, let's explore the more practical application of these concepts, normalization, and the form we can produce 1NF, 2NF, 3NF and 4NF. First we look at the differences between them.

Recall that the definition BCNF is:
For every non-trivial FD {A1 . . . An} → {B1 . . . Bm} for R {A1, . . ., An } is a superkey for R.
In other words: the left side of a FD needs to contain a key.

The definition of 3NF is:
For every non-trivial FD {A1 . . . An} → {B1 . . . Bm} for R, EITHER {A1, . . ., An } is a superkey OR the right side consists of prime attributes only.
A prime attribute is an attribute that is a member of a key.

In practice today, the process we just explored is referred to as “Normalization”. The term Normalization is a interchangeable with Decomposition.
Commonly, modern database schemas are normalized into “Normal Form” which is a reference to 1NF, 2NF, 3NF or 4NF.

Here we explore 1NF, 2NF, 3NF and discuss 4NF as well.

Link to slides used in this presentation: https://drive.google.com/file/d/1ew1S...

Book used in this course: Garcia-Molina, Hector. Database systems: the complete book. Pearson Education India, 2008.
https://www.amazon.com/Database-Syste...