The document discusses the history of database normalization. It explains the concepts of first normal form (1NF), second normal form (2NF), and third normal form (3NF). 1NF requires eliminating duplicate columns and creating separate tables for related data. 2NF builds on 1NF by removing subsets of data that apply to multiple rows. 3NF builds on 1NF and 2NF by removing columns not dependent on the primary key. The document notes that fourth and fifth normal forms are not commonly used, while sixth normal form only applies to alien databases. It concludes by stating that denormalization is key to data warehousing.

1. Databases – A Historical Perspective
Postgresql East - 2010
Philadelphia, PA

2. Databases – A Historical Perspective
Part Two
Why be normal?

3. Databases – A Historical Perspective
•The Normal Forms
• Normalization Workshop

4. Databases – A Historical Perspective
Normal Forms
The truth,
The whole truth,
And nothing but the truth.

5. Databases – A Historical Perspective
First Normal Form (1NF) sets the
very basic rules for an organized
database:
1. Eliminate duplicative columns from
the same table.
2. Create separate tables for each
group of related data and identify each
row with a unique column (the primary
key).

6. Databases – A Historical Perspective
Second Normal Form 2NF:
1. Remove subsets of data that
apply to multiple rows of a table
and place them in separate tables.
2. Create relationships between
these new tables and their
predecessors through the use of
foreign keys.

7. Databases – A Historical Perspective
Third Normal Form:
1. Meet the requirements of both
1NF and 2NF
2. Remove columns that are not
fully dependent upon the primary
key.

8. Databases – A Historical Perspective
4th and 5th Normal Form –
These are data purity abstractions
which are not routinely used in
production databases.

9. Databases – A Historical Perspective
6th Normal Form –
Found only in alien databases.

10. Databases – A Historical Perspective
"The key, the whole key,
and nothing but the key,
so help me Codd."

11. Databases – A Historical Perspective
And, a note about data
warehousing…
De-normalization is a key
tenet of data warehousing.

12. Databases – A Historical Perspective
BRAINSTORM!!!

13. Databases – A Historical Perspective
Questions?
Comments?

14. Databases – A Historical Perspective
End
Of
Part
Two