3N Normalized Databases

1. 3N Normalized Databases
MINISTÈRE DE L’ENSEIGNEMENT SUPÉRIEUR DE LA RECHERCHE SCIENTIFIQUE
UNIVERSITÉ TUNIS EL MANAR
‫بتونس‬ ‫للمهندسين‬ ‫الوطنية‬ ‫المدرسة‬
ÉCOLE NATIONALE D’INGÉNIEURS DE TUNIS
By:
Rami MAHJOUBA
Achraf CHEBIL

2. • Overview
 Introduction
 First Normal Form (1NF)
 Second Normal Form (2NF)
 Third Normal Form (3NF)
 Conclusion

3. • Introduction
 Organizing relations and attributes
 To improve data integrity
 Eliminate data redundancy
 Inappropriate functional dependencies
What is Normalization?

4. • Introduction
EDGARD F. CODD.
 Invented the relational model
 Introduced normalization
 Proposed 3 initial normal forms and the Boyce-Codd form
History overview

5. • Introduction
Initial Normal Forms
 First Normal Form (1NF)
 Second Normal Form (2NF)
 Third Normal Form (3NF)

6. • Introduction
Additional Normal Forms
 Boyce-Codd Normal Form (BCNF)
 Fourth Normal Form (4NF)
 Fifth Normal Form (5NF)

7. • First Normal Form (1NF)
 Data cannot be broken down further(atomic)
 Columns have no repeating/similar data
 Each row is unique
 Each field has a unique name
Rules For 1NF

8. • First Normal Form (1NF)
Original Invoice Table
Invoice Number Date Amount Customer ID Customer Name Item
125 09/15/2016 1000 17 Harry Potter Wand, Cloak
126 09/16/2016 150 21 Percy Jackson Bolt
127 09/16/2016 380 12 Katniss Everdeen Bow, Arrow
128 09/16/2016 850 17 Harry Potter Broom
Break Down

9. • First Normal Form (1NF)
Revised Invoice Table
Invoice Number Date Amount Customer ID Customer First Name Customer Last Name Item
125 09/15/2016 1000 17 Harry Potter Wand,
Cloak
126 09/16/2016 150 21 Percy Jackson Bolt
127 09/16/2016 380 12 Katniss Everdeen Bow,
Arrow
128 09/16/2016 850 17 Harry Potter Broom
Atomic

10. • First Normal Form (1NF)
Revised Invoice Table
Invoice
Number
Date Amount Customer ID Customer First Name Customer Last Name Item
125 09/15/2016 1000 17 Harry Potter Wand
125 09/15/2016 1000 17 Harry Potter Cloak
126 09/16/2016 150 21 Percy Jackson Bolt
127 09/16/2016 380 12 Katniss Everdeen Bow
127 09/16/2016 380 12 Katniss Everdeen Arrow
128 09/16/2016 850 17 Harry Potter Broom
No
Repeating
Data
Unique
Rows

11. • Second Normal Form (2NF)
 Should be in 1NF
 Non-key attributes are functional dependent on primary key
Rules For 2NF

12. • Second Normal Form (2NF)
1NF invoice table
Invoice
Number
Date Amount Customer ID Customer First Name Customer Last Name Item
125 09/15/2016 1000 17 Harry Potter Wand
125 09/15/2016 1000 17 Harry Potter Cloak
126 09/16/2016 150 21 Percy Jackson Bolt
127 09/16/2016 380 12 Katniss Everdeen Bow
127 09/16/2016 380 12 Katniss Everdeen Arrow
128 09/16/2016 850 17 Harry Potter Broom
Non-dependant

13. • Second Normal Form (2NF)
2NF invoice table + Invoice table
Invoice
Number
Date Amount Customer
ID
Customer
First Name
Customer Last Name
125 09/15/2016 1000 17 Harry Potter
126 09/16/2016 150 21 Percy Jackson
127 09/16/2016 380 12 Katniss Everdeen
128 09/16/2016 850 17 Harry Potter
Invoice
Number
Item
125 Wand
125 Cloak
126 Bolt
127 Bow
127 Arrow
128 Broom
Foreign Key

14. • Third Normal Form (3NF)
 Should be in 2NF
 No Transitive dependencies
Rules For 3NF

15. • Third Normal Form (3NF)
2NF invoice table
Invoice
Number
Date Amount Customer
ID
Customer
First Name
Customer Last Name
125 09/15/2016 1000 17 Harry Potter
126 09/16/2016 150 21 Percy Jackson
127 09/16/2016 380 12 Katniss Everdeen
128 09/16/2016 850 17 Harry Potter
Transitive dependency
X Y
Y Z
X Z

16. • Third Normal Form (3NF)
3NF invoice table + Customers table
Invoice
Number
Date Amount Customer
ID
125 09/15/2016 1000 17
126 09/16/2016 150 21
127 09/16/2016 380 12
128 09/16/2016 850 17
Customer
ID
Customer First
Name
Customer last
Name
17 Harry Potter
21 Percy Jackson
12 Katniss Everdeen
17 Harry Potter
Foreign Key

17. • Conclusion
We have seen how Database Normalization can:
 Decrease redundancy
 Increase efficiency
 Reduce anomalies
By implementing three of all the different levels of normalization called
Normal Forms. The first three NF’s are usually sufficient for most small
to medium size applications.