1. Logical Data Modeling – Normalization
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2. Outline Logical Data Modeling – Normalization First Normal Form
Second Normal Form
Third Normal Form
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3. Normalization
Rules/Conditions that every entity and its attributes must satisfy:
…plus manipulations to “fix” violations
Violation fixes can be applied iteratively, until no violations remain.
Fixes usually involve creating new entities
“Algorithmic” strategy to achieve a good data-model:
Complete, non-redundant, “business” logic, etc…
Elimination of update anomalies
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4. Normalization
Usually normalization is applied as a series of checks after an initial data model is proposed
Often, primary entities of a data model are clear
Provides “good-practice patterns” for data-model manipulation and representation challenges
Usually do not start with a “universal” table for the entire data-model
…but one or more entities in a logical data model may need to be fixed.
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5. Extended Example
Data Modeling Essentials, Ch2
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6. Initial Drug Expenditure Model
… plus lots of business logic, that I’ll explain as we go…
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7. Normalization 1st Normal Form (1NF): 2nd Normal Form (2NF):
One fact per attribute
Entity instances are unique
No repeated attributes
2nd Normal Form (2NF):
1st Normal Form, plus
No partial (primary-key) determinants
3rd Normal Form (3NF):
2nd Normal Form, plus
No non-primary-key determinants
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8. 1st Normal Form (1NF) One fact, one attribute
Compound attributes are exploded to new columns
Clean-up representations, hidden attributes, dependent attributes
Entity instances are unique
Every instance is uniquely defined by its primary-key
No repeated attributes
Repeated attributes become instances of new entity
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9. One fact per attribute
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10. One fact per attribute
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11. Identify Primary-Key
Hospital Number and Operation Number uniquely identify the operation “event”
Operation Number is managed by each Hospital independently.
Hospital Number and Operation Number are underlined.
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12. No repeated attributes
Identify and remove groups of repeated attributes:
Make new entity with repeated groups as instances
Include the primary-key of the original table in the new entity’s attributes
Identify the new entity’s primary-key
Original primary-key plus…?
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13. No repeated attributes
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14. 1st Normal Form (1NF) Entity instances are unique (PK)
One fact per attribute
No repeated attributes
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15. 2nd Normal Form (2NF) No partial primary-key determinants
What attributes are completely determined by part of a primary-key?
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16. Determinants
A determinant is any identifier attribute (or set of identifier attributes) of an entity that determines other attributes’ values.
This should be true conceptually, not just for the current set of instances
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17. 2nd Normal Form (2NF) No partial primary-key determinants
Create new table for determinant and determined attributes, determinant as PK
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18. 2nd Normal Form (2NF) No partial primary-key determinants
What other attributes are completely determined by part of a primary-key?
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19. 2nd Normal Form (2NF) No partial primary-key determinants
What other attributes are completely determined by part of a primary-key?
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20. 2nd Normal Form (2NF)
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21. 3rd Normal Form (3NF) No non-primary-key determinants
What attributes are determined by something other than the primary key of an entity?
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22. 3rd Normal Form (3NF) No non-primary-key determinants
What attributes are determined by something other than the primary key of an entity?
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23. 3rd Normal Form (3NF) No non-primary-key determinants
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24. 3rd Normal Form (3NF)
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25. Exercise From the course data-folder:
Drug_Expenditure_UniversalTable.xlsx
Small instantiation of the data for the example
Step-by-step, normalize this universal table to 3rd normal form.
Use a separate sheet for each entity
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26. Homework Manipulate a new universal table to 3NF Submit:
Class_Registration_UniversalTable.xlsx
Submit:
an explicit list of the “business” logic used to determine determinants
a compact description (see slide 21) of the entities and their attributes
an entity relationship diagram (see slide 22), and
an excel file with each entity represented as a table in a worksheet, populated from original universal table.
Due Feb 1st, 10am
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