1. Information Systems Development MIS331
BMGT Data Modeling
Information Systems Development MIS331
Computer-Aided Software Design
Data Normalization
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MIS331

2. Agenda Good news and bad news about CASE CASE adoption issues
BMGT Data Modeling
Agenda
Good news and bad news about CASE
CASE adoption issues
CASE components and functions
Where does it fit in?
Oracle Designer/2000 Overview
Data Normalization Techniques
Issues concerning Normalization
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MIS331

3. Computer-Aided Software Engineering
BMGT Data Modeling
Computer-Aided Software Engineering
Objectives of CASE…
- Improve system quality
- Decrease production and development time
- Reduce level of effort needed for testing
- Improve integration of multiple development projects
- Improve documentation
- Promote formalized development standards
- Improve project management activities
- Reduce efforts associated with maintenance
- Allow for reusable code to become a reality
- Improve system portability
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MIS331

4. The Good News and the Bad News
BMGT Data Modeling
The Good News and the Bad News
Now for the bad news…
CASE is extremely expensive
Initial training costs are extremely high
Organizational confidence in IS is low
Methodology standards do not exist
CASE is often viewed as a threat
CASE does not have a great past history
First, the good news…
shorter development times are possible
CASE does improve productivity
CASE does improve quality
Employee skill inventories improve
Portability is easier
Management of SDLC is easier
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MIS331

5. CASE Components Diagramming tools Screen and report generators
BMGT Data Modeling
CASE Components
Diagramming tools
process, data, control diagrams
Screen and report generators
prototyping for “look and feel” issues
Analysis tools
checks for errors, omissions, inconsistencies, etc.
Repository
where it is all stored
Documentation generators
guess what these do...
Code generators
COBOL, C++, VB, HTML, Pascal
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MIS331

6. How does it all fit together?
BMGT Data Modeling
How does it all fit together?
Without CASE…
Analyst spends most of the time maintaining the code and the documentation
change the code…change the documentation
With CASE…
Analyst focuses primarily on maintaining the models
change the model…everything else changes automatically
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MIS331

7. Oracle Designer/2000 Current release is called Oracle Designer
BMGT Data Modeling
Oracle Designer/2000
Current release is called Oracle Designer
Installation costs can exceed $50,000
Multi-user Repository
Code generators currently support multiple languages
C++, COBOL, Fortran, Visual Basic, HTML
Complete life-cycle spanning capabilities
Includes reverse engineering modules
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MIS331

8. Data Normalization Normalization is a process of data “filtration”
BMGT Data Modeling
Data Normalization
Normalization is a process of data “filtration”
Each step filters a specific data characteristic out of the attribute set
When complete, the data set is organized into a simple group of stable data structures…sometimes too stable
Why do we normalize?
primarily to minimize data redundancy
minimizing redundancy improves database integrity
normalization helps identify missing entities and relationships
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MIS331

9. Data Normalization Process
BMGT Data Modeling
Data Normalization Process
Repeating
Elements
Raw
Data
Elements
Functional
Dependencies
First
Normal
Form (1NF)
Transitive
Dependencies
Second
Normal
Form (1NF)
Third
Normal
Form (1NF)
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MIS331

10. BMGT Data Modeling
First Normal Form - 1NF
ORDER
ORDER NUMBER
ORDER DATE
MEMBER NUMBER
MEMBER NAME
MEMBER ADDRESS GROUP
STREET
P.O. BOX NO.
CITY
STATE
ZIPCODE
PHONE
ORDER SUBTOTAL
SALES TAX
AMOUNT PREPAID
ORDER TOTAL
ORDER
ORDER NUMBER
ORDER DATE
MEMBER NUMBER
MEMBER NAME
MEMBER ADDRESS GROUP
STREET
P.O. BOX NO.
CITY
STATE
ZIPCODE
PHONE
PRODUCT (repeats 1-n times)
PRODUCT NO.
MEDIA CODE
DESCRIPTION
QUANTITY
UNIT PRICE
EXTENSION
ORDER SUBTOTAL
SALES TAX
AMOUNT PREPAID
ORDER TOTAL
ORDER
ORDER NUMBER
ORDER DATE
MEMBER NUMBER
MEMBER NAME
MEMBER ADDRESS GROUP
STREET
P.O. BOX NO.
CITY
STATE
ZIPCODE
PHONE
PRODUCT (repeats 1-n times)
PRODUCT NO.
MEDIA CODE
DESCRIPTION
QUANTITY
UNIT PRICE
EXTENSION
ORDER SUBTOTAL
SALES TAX
AMOUNT PREPAID
ORDER TOTAL
An entity is in 1NF if there are no elements or groups of elements that repeat for a single occurrence of the entity.
Any elements that repeat actually describe an occurrence of a separate entity.
probably one that hasn’t yet been defined in the data model
ORDERED PRODUCT
ORDER NUMBER+
PRODUCT NO.+
MEDIA CODE
DESCRIPTION
QUANTITY
UNIT PRICE
EXTENSION
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MIS331

11. BMGT Data Modeling
Second Normal Form - 2NF
An entity is in 2NF if it has a combination key and all non-key elements are derived by the full key, not part of it.
no partial functional dependencies
ORDERED PRODUCT
ORDER NUMBER+
PRODUCT NO.+
MEDIA CODE
DESCRIPTION
QUANTITY
UNIT PRICE
EXTENSION
ORDERED PRODUCT
ORDER NUMBER+
PRODUCT NO.+
MEDIA CODE
DESCRIPTION
QUANTITY
UNIT PRICE
EXTENSION
ORDERED PRODUCT
ORDER NUMBER+
PRODUCT NO.+
MEDIA CODE
DESCRIPTION
QUANTITY
UNIT PRICE
EXTENSION
ORDERED PRODUCT
ORDER NUMBER+
PRODUCT NO.+
MEDIA CODE
QUANTITY
UNIT PRICE
EXTENSION
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MIS331

12. Quantity x Unit Price = Extension
BMGT Data Modeling
Third Normal Form - 3NF
An entity is in 3NF if the values of its non-key elements are not dependent on any other non-key elements.
only necessary to check entities with non-combination keys
most common transitive dependency is a calculated (derived) field.
ORDERED PRODUCT
ORDER NUMBER+
PRODUCT NO.+
MEDIA CODE
QUANTITY
UNIT PRICE
EXTENSION
ORDERED PRODUCT
ORDER NUMBER+
PRODUCT NO.+
MEDIA CODE
QUANTITY
UNIT PRICE
EXTENSION
ORDERED PRODUCT
ORDER NUMBER+
PRODUCT NO.+
MEDIA CODE
QUANTITY
UNIT PRICE
Quantity x Unit Price = Extension
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MIS331

13. De-Normalization Y-T-D Sales = S(Daily Sales to date)
BMGT Data Modeling x
De-Normalization
Once the data is in 3NF we must concern ourselves with balancing minimum redundancy with maximum performance.
consider the problem of year-to-date sales
Y-T-D Sales = S(Daily Sales to date)
Assume Daily Sales = approximately 1,000 transactions per day...
If the report is run on January 2 at day end, the query needs to add
approximately 2,000 transactions to reach a total.
If each transaction takes 0.01 seconds to tally, then the report will take:
2,000 transactions x 0.01 seconds = 20 seconds
If, however, the report is requested on December 31 at day end, the query
needs to add approximately 365,000 transactions to reach a total.
Now the time to receive a response will be:
365,000 transactions x 0.01 seconds = 3,650 seconds = hours
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MIS331

14. BMGT Data Modeling
So…...
Certain situations may require the designer to de-normalize some data elements.
How can we solve this year-to-date thing?
De-normalize the data elements to allow for the tabulation and storage of month-to-date totals.
This action will purposely create a file full of fields that are calculated and thus, not in 3NF.
But...
Total time per monthly calculation = 5.07 minutes
Total time for y-t-d report on December 31 = 0.12 seconds
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MIS331

15. Next Classes... More on CASE tools on Thursday
BMGT Data Modeling
Next Classes...
More on CASE tools on Thursday
Case #3 Presentation - Group C - on Tuesday
Knowledge Demonstration next Thursday, 2/27
Spring Break first week of March
Case #4 Presentation - Group D - on 3/11
Chapter 8 for class on 3/13
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