1. Rules of Database Normalization
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2. Overview What is Normalization?
What is the objective of Normalization?
Why is Normalization in a database important?
What are NORMAL FORMS?
How do we accomplish Normalization in our database?
Are there times when Normalization is unnecessary?
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3. What is Normalization?
Normalization refers to the process of creating an efficient, reliable, flexible, and appropriate “relational” structure for storing information in a “relational” data structure.
Normalization usually involves dividing a database into two or more tables and defining the relationship between the tables.
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4. What is the objective of Normalization?
The objective is to isolate data so that additions, deletions, and modifications of a field can be made in just one table and then propagated through the rest of the database via the defined relationships.
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5. Why is Normalization in a database important?
Normalization removes redundant data from your tables in order to improve storage efficiency.
Normalization removes redundant data and improves data integrity.
Normalization removes redundant data and helps in maintenance problems. Example: If data that exists in more than one place must be changed, the data must be changed in exactly the same way in all locations.
Finally, Normalization removes redundant data and improves the scalability of your database.
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6. What are NORMAL FORMS?
A series of logical steps to normalize data tables.
First Normal Form-1NF
Second Normal Form-2NF
Third Normal Form-3NF
Fourth Normal Form-4NF
Fifth Normal Form-5NF
We will learn the First, Second and Third Normal Forms
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7. What is the First Normal Form?
The definition of the first Normal Form is as follows
There are no repeating groups.
All of the key attributes are defined.
All attributes are dependent on the primary key.
Example on the next slide.
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8. How do we accomplish First Normal Form? Look at this example.
Project Number
Project
Name
Employee
Number
Name-1
Rate
Category-1
Hourly
Rate-1
Name 2
Category
1023, 1056
Madagascar
Travel site and
Online
Estate Agency 11
Julius Wilson A
$60
Monica Jefferson B
$50
1023
Travel site 16
Daniel Moore C
$40
1056
Online Estate
Agency 17
Charles Saul D
$30
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9. Notice the repeating Groups.
Project Number
Project
Name
Employee
Number
Name-1
Rate
Category-1
Hourly
Rate-1
Name 2
Category
1023, 1056
Madagascar
Travel site and
Online
Estate Agency 11
Julius Wilson A
$60
Monica Jefferson B
$50
1023
Travel site 16
Daniel Moore C
$40
1056
Online Estate
Agency 17
Charles Saul D
$30
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10. This is our solution to eliminating the repeating groups
Project Number
Project
Name
Employee
Number
Rate
Category
Hourly
1023
Madagascar
Travel site 11
Julius Wilson A
$60 12
Monica Jefferson B
$50 16
Daniel Moore C
$40
1056
Online Estate
Agency 17
Charles Saul D
$30
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11. How can we set our Primary Key?
Project Number
Project
Name
Employee
Number
Rate
Category
Hourly
1023
Madagascar
Travel site 11
Julius Wilson A
$60 12
Monica Jefferson B
$50 16
Daniel Moore C
$40
1056
Online Estate
Agency 17
Charles Saul D
$30
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12. Can this be our Primary Key?
Project Number
Project
Name
Employee
Number
Rate
Category
Hourly
1023
Madagascar
Travel site 11
Julius Wilson A
$60 12
Monica Jefferson B
$50 16
Daniel Moore C
$40
1056
Online Estate
Agency 17
Charles Saul D
$30
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13. Or, can this be our Primary Key?
Project Number
Project
Name
Employee
Number
Rate
Category
Hourly
1023
Madagascar
Travel site 11
Julius Wilson A
$60 12
Monica Jefferson B
$50 16
Daniel Moore C
$40
1056
Online Estate
Agency 17
Charles Saul D
$30
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14. Solution-We need both as our Primary Keys.
Project Number
Primary Key
Project
Name
Employee
Number
Rate
Category
Hourly
1023
Madagascar
Travel site 11
Julius Wilson A
$60 12
Monica Jefferson B
$50 16
Daniel Moore C
$40
1056
Online Estate
Agency 17
Charles Saul D
$30
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15. Is our table in First Normal Form?
Project Number
Primary Key
Project
Name
Employee
Number
Rate
Category
Hourly
1023
Madagascar
Travel site 11
Julius Wilson A
$60 12
Monica Jefferson B
$50 16
Daniel Moore C
$40
1056
Online Estate
Agency 17
Charles Saul D
$30
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16. What is Second Normal Form
A table is in 2nd Normal Form if:
It is in 1st normal form.
It includes no partial dependencies (where an attribute is dependent on only a part of a primary key).
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17. Does it include partial dependencies? Do you notice anything else?
Project Number
Primary Key
Project
Name
Employee
Number
Rate
Category
Hourly
1023
Madagascar
Travel site 11
Julius Wilson A
$60 12
Monica Jefferson B
$50
Madagascat 16
Daniel Moore C
$40
1056
Online Estate
Agency 17
Charles Saul D
$30
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18. Look at “Project Name” Row 3. Also look at Hourly Rate
Look at “Project Name” Row 3. Also look at Hourly Rate? What about data integrity?
Project Number
Primary Key
Project
Name
Employee
Number
Rate
Category
Hourly
1023
Madagascar
Travel site 11
Julius Wilson A
$60 12
Monica Jefferson B
$50
Madagascat 16
Daniel Moore C
$40
1056
Online Estate
Agency 17
Charles Saul D
$30
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19. Step One: Project Name is only Dependent on Project
Employee-Project Table
Project
Name
Employee
Number
1023 11 12 16
1056 17
Project Name is only
Dependent on Project
Number; so, we create a
“Employee Project Table.”
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20. Step Two: Notice that “Project Name” is dependent on only
Project Table
Project Number
Primary Key
Project
Name
1023
Madagascar
Travel site
1056
Online Estate
Agency
Notice that “Project Name”
is dependent on only
“Project Number.”
We create our “Project Table”
With Project Number as our
Primary Key. Look at the space
we have saved. What else have
we done?
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21. Step Three: Notice that Employee Name, Rate Category,
Employee Table
Employee
Number
Primary Key
Name
Rate
Category
Hourly 11
Julius Wilson A
$60 12
Monica
Jefferson B
$50 16
Daniel Moore C
$40 17
Charles Saul D
$30
Notice that Employee
Name, Rate Category,
and Hourly Rate are
dependent on
Employee Number.
We create our
“Employee Table”
with
Employee Number
as our Primary Key.
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22. Are we now in Second Normal Form?
Employee Project
Table
Employee Project
Table
Project Table
Project Table
Employee Table
Project
Name
Primary Key
Employee
Number Primary Key
1023 11 12 16
1056 17
Project
Name
Primary Key
Employee
Number Primary Key
1023 11 12 16
1056 17
Project Number
Primary Key
Project
Name
1023
Madagascar
Travel site
1056
Online Estate
Agency
Employee
Number
Primary Key
Name
Rate
Category
Hourly 11
Julius Wilson A
$60 12
Monica Jefferson B
$50 16
Daniel Moore C
$40 17
Charles Saul D
$30
Is it in First Normal Form and does it includes no partial
Dependencies?
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23. Now, What is Third Normal Form?
It is in SECOND Normal Form.
It contains no transitive dependencies (where a non-key attribute is dependent on another non-key attribute).
Let’s see where we begin.
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24. Let’s take another look at what we have.?
Employee Project
Table
Employee Project
Table
Project Table
Project Table
Employee Table
Project
Name
Primary Key
Employee
Number Primary Key
1023 11 12 16
1056 17
Project Number
Primary Key
Project
Name
1023
Madagascar
Travel site
1056
Online Estate
Agency
Employee
Number
Primary Key
Name
Rate
Category
Hourly 11
Julius Wilson A
$60 12
Monica Jefferson B
$50 16
Daniel Moore C
$40 17
Charles Saul D
$30
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25. Let’s look at the Employee Project Table
Can we do anything else with this table?
Employee Project
Table
Project
Name
Primary Key
Employee
Number Primary Key
1023 11 12 16
1056 17
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26. Let’s Look at the Project Table.
Can we do anything else with this table?
Project Table
Project Number
Primary Key
Project
Name
1023
Madagascar
Travel site
1056
Online Estate
Agency
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27. Let’s look at the Employee table
Can we further normalize this table?
Employee Table
Employee
Number
Primary Key
Name
Rate
Category
Hourly 11
Julius Wilson A
$60 12
Monica Jefferson B
$50 16
Daniel Moore C
$40 17
Charles Saul D
$30
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28. See what we can do with the employee table.
Let’s make an “Rate” Table
Employee Table
Rate Table
We have now reduced
the possibility of
Employees being paid
Incorrectly. Our database
Will have more integrity.
Employee
Number
Primary Key
Name
Rate
Category 11
Julius Wilson A 12
Monica Jefferson B 16
Daniel Moore C 17
Charles Saul D
Rate
Category
Primary Key
Hourly A
$60 B
$50 C
$40 D
$30
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29. That’s It! Our data is now in 3NF.. Ready to be used in a DBMS…
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