Basic Database Normalization

1. E R M O D E L L I N G & D B N O R M A L I Z A T I O N
DATABASE NORMALIZATION

2. NORMALIZATION
 Process for evaluating and correcting table structures to
minimize data redundancies
 Reduces data Anomalies
 Brings a database to a consistent state
 Works through a series of stages called normal forms:
 First normal form (1NF)
 Second normal form (2NF)
 Third normal form (3NF)
The higher you go the better 3rd normal form is better than 2  2 is
better than 1

3. REASONS FOR NORMALIZATION
 Data Redundancy

4. RESONS FOR NORMALIZATION
 Relations become progressively more restricted (stronger)
in format and also less vulnerable to update anomalies.
 One peace of information is stored in one location / place

5. KEYWORDS
 Determinant  determines the value of other attributes
in the tuples.
 Functional Dependency Describes relationship
between attributes in a relation.

6. EXAMPLE OF DATABASE ANOMALIES
 Update Anomalies
 Delete Anomalies
 Insert Anomalies

7. UPDATE ANOMALIES
 Occurs when data is scattered
 Not linked together properly
 Leaves database inconsistent

8. DELETE ANOMALIES
 Parts of data not deleted
 Unawareness

9. INSERT ANORMALIES
 Insert Data in a record that does not exist

10. FIRST NORMAL FORM
 All attributes in a relation must have atomic
domains
 Purpose is to remove repeating groups in relation
 Each row and column contains one and only one
value
 Gets rid of extra , make data as small as it can get
 All key attributes are defined
 No repeating column

11. FIRST NORMAL FORM
 Rearrange the table to convert to First normal form
Each
attribute
must
contain
only one
single
value
form its
predefine
d
domain.

12. EXAMPLE 2
 What's the wrong with the table?

13. COLUMNS REMOVED
 1st Normal form
Primary Key

14. SECOND NORMAL FORM
 Remove partial dependencies
 Every non-primary-key attribute is fully functionally dependent
on the primary key.
 No attribute is dependent on only a portion of primary key
 Key Terms
 Prime Attribute  An attribute which is part of
primary key.
 Non Prime Attribute  Any attribute which is not
part of the primary key.
 Every Non-Prime attribute SHOULD be fully
functionally dependent on the prime key attribute.
 In short Non key attributes should depend on full
primary key

15. EXAMPLE
 .

16. EXAMPLE ..SECOND NORM
 The relation is broken into two thereby removing
partial dependency.

17. EXAMPLE 2
 Person Project

18. CONTINUATION 2ND NORM
 .

19. THIRD NORMAL FORM
 All non key attributes should nontransitively
dependent on the primary key.

20. RESULT
 .