1. Data normalization. Integrity and Robustness.
Creating Databases
Data normalization. Integrity and Robustness.
Work session.
Homework: Prepare short presentation on enhancement projects. Continue working on implementation.

2. What is normalization?
Data analysis is a process that prepares a data model for implementation as a simple, non-redundant, flexible, and adaptable database. The specific technique is called normalization.
Normalization is a data analysis technique that organizes data attributes such that they are grouped to form non-redundant, stable, flexible, and adaptive entities.
ASSUMES that you have reports, input forms that capture all the information.
This and following charts are from information systems analysis course. Don't be overcome by the language.
This is to show you the process, that there is a process—it isn't guess work.

3. Goals of normalization
Have well-defined tables—at most one value for each field.
Store each item of information exactly one place so if/when it changes, only have to change one place.
Relationships are valid: foreign keys refer to existing primary keys.
Don't store items that can be calculated so making changes is simplified.

4. Process of defining database
Generally starts with the desired end products (sometimes called artifacts)
Reports
Forms
May be from original, possibly even non-automated version of application
May be from combination of applications. Goal is to produce single database that serves multiple uses.

5. But… Problems are common.
Example: change address [one place] but old information persists.
Your experience?

6. Normalization process
First step is to do what is necessary to get each entity into 1st normal form:
An entity is in first normal form (1NF) if there are no attributes that can have more than one value for a single instance of the entity. Any attributes that can have multiple values actually describe a separate entity, possibly an entity and relationship.
Common situation is so-called multiple values, such as distinct items in an order (distinct beneficiaries, game-machines)
Action is to create new entity
In the typical product order case, there can be multiple items ordered in each 'order. So these are extracted.

7. Modifying model to 1st NF
The primary key for the new table is a so-called concatenated key. Here it is the promotion and the title.
So notice that the primary key for the title promotion records consist of two foreign keys=keys pointing to other tables.
Many items (titles)
Associative entity:
Use combination of keys for
new (concatenated) key

8. Moving to 2nd NF
If you do not have any concatenated keys, no work is needed. Model is already in 2nd NF.
If you do have any concatenated (combination) keys, you need to examine these entities.
An entity is in second normal form (2NF) if it is already in 1NF and if the values of all nonprimary key attributes are dependent on the full primary key—not just part of it. Any nonkey attributes that are dependent on only part of the primary key should be moved to any entity where that partial key is actually the full key. This may require creating a new entity and relationship on the model.
The process of getting something in 1NF may have carried over data that appears somewhere else. You don't want data twice. (You may choose to make whole databases redundant, for efficiency of access or for backup, but that is done separately.)

9. Moving to 2nd NF Some attributes relate to the
product itself, not the fact that the
product is part of this order.
Remove these attributes.
To say the same thing a slightly different way: you don't need this product only data in the ordered product record.

10. So…
In my store example, the ordered items records would NOT have information just relating to the order or just relating to the product.

11. Moving to 3rd NF
Make sure that all non-primary attributes depend just on the key, not, for example, on another attribute.
An entity is in third normal form (3NF) if it is already in 2NF and if the values of its nonprimary key attributes are not dependent on any other non-primary key attributes. Any nonkey attributes that are dependent on other nonkey attributes must be moved or deleted. Again, new entities and relationships may have to be added to the data model.
Typical example is something that can be calculated.

12. Example of move to 3rd NF
First of two examples

13. Example of move to 3rd NF
Second of two examples.

14. The whole ER diagram this particular example.
MEMBER
Primary Key
Member-Number [PK1]
Non-Key Attributes
Member-Name
Member-Status
Member-Street-Address
Member-Post-Office-Box
Member-City
Member-State
Member-Zip-Code
Member-Daytime-Phone-Number
Member-Date-of-Last-Order
Member-Balance-Due
Member-Credit-Card-Type
Member-Credit-Card-Number
Member-Credit-Card-Expire-Date
Member-Bonus-Balance-Available
Audio-Category-Preference
Audio-Media-Preference
Date-Enrolled
Expiration-Date
Game-Category-Preference
Game-Media-Preference
Number-of-Credits-Earned
Video-Category-Preference
Video-Media-Preference
Agreement-Number [FK]
Privacy-Code
-Address
MEMBER ORDER
Order-Number [PK1]
Order-Creation-Date
Order-Fill-Date
Shipping-Address-Name
Shipping-Street-Address
Shipping-City
Shipping-State
Shipping-Zip
Shipping-Instructions
Order-Sub-Total
Order-Sales-Tax
Order-Shipping-Method
Order-Shipping-&-Handling-Cost
Order-Status
Order-Prepaid-Amount
Order-Prepayment-Method
Promotion-Number [FK]
Member-Number [FK]
Member-Number Member-Number [FK]
PRODUCT
Product-Number [PK1]
"Universal-Product-Code (Alternate Key)"
Quantity-in-Stock
Product-Type
Suggested-Retail-Price
Default-Unit-Price
Current-Special-Unit-Price
Current-Month-Units-Sold
Current-Year-Units-Sold
Total-Lifetime-Units-Sold
VIDEO TITLE
Product-Number [PK1] [FK]
Producer
Director
Video-Category
Video-Sub-Category
Closed-Captioned
Language
Running-Time
Video-Media-Type
Video-Encoding
Screen-Aspect
MPA-Rating-Code
AUDIO TITLE
Artist
Audio-Category
Audio-Sub-Category
Number-of-Units-in-Package
Audio-Media-Code
Content-Advisory-Code
GAME TITLE
Manufacturer
Game-Category
Game-Sub-Category
Game-Platform
Game-Media-Type
Number-of-Players
Parent-Advisory-Code
TRANSACTION
Transaction-Reference-Number [PK1]
Transaction-Date
Transaction-Type
Transaction-Description
Transaction-Amount
Order-Number [FK]
TITLE
Title-of-Work
Title-Cover
Catalog-Description
Copyright-Date
Entertainment-Category
Credit-Value
MEMBER ORDERED PRODUCT
Order-Number [PK1] [FK]
Product-Number [PK2] [FK]
Quantity-Ordered
Quantity-Shipped
Quantity-Backordered
Purchase-Unit-Price
Credits-Earned
MERCHANDISE
Merchandise-Name
Merchandise-Description
Merchandise-Type
Unit-of-Measure
AGREEMENT
Agreement-Number [PK1]
Agreement-Expire-Date
Agreement-Active-Date
Fulfillment-Period
Required-Number-of-Credits
PROMOTION
Promotion-Number [PK1]
Promotion-Release-Date
Promotion-Status
Promotion-Type
3NF Member Services (Entity
Relation Subject Area)
SA/2001
Tue May 02, :41
Comment
Sandra Shepherd
TITLE PROMOTION
Promotion-Number [PK2] [FK]
places
binds
features
is featured as
is a
has
conducted
responds to
generates
sold as
sells
The whole ER diagram this particular example.

15. Normalization
…. is a process. It is [somewhat] mechanical. There is chance that your model may be in 1st, 2nd, or even 3rd without action or much action on your part, but it can be good to go through the process.
Note: Some may argue for certain redundancies, for example, storing a calculated value. Why or why not?
Answers to question?

16. About assignment
You can specify conditions that simplify your application
For a course catalog application, allow 0 or 1 pre-req, not unlimited number.
Upload files using Filezilla. I will demonstrate file upload code and related issues. ?
Do some checking of user input. I will expect more for your final project.

17. Classwork/Homework
Prepare short presentation on enhancement project, including Entity-Relationship diagrams (which may not have changed from mine) and Data Flow Diagram (which probably did change)
Work on enhancement projects.