1. Relational Database Appendix

2. ER Diagram Entity/relation Entity Subtype Relationship
Composite Entity
Bus 311: Fall 2003

3. Shorthand Description
State (StateAbbrev, StateName, EnteredUnionOrder, StateBird, StatePopulation)
Capital (CapitalName, StateAbbrev, YearDesignated, PhoneAreaCode, CapitalPopulation)
Foreign Key: StateAbbrev to State relation
City (StateAbbrev, CityName, CityPopulation)
Crop (CropName, Exports, Imports)
Production (StateAbbrev, CropName, Quantity)
Foreign Key: CropName to Crop relation
Shipping (StateAbbrev, OceanShoreline, ExportTonnage, ImportTonnage)
Bus 311: Fall 2003

4. Integrity Constraints
Ideally DBMS enforces integrity
MS Access does a pretty good job
Primary key constraints
Must be unique and non-null
Referential integrity
Each no-null foreign key must match a primary key
No ‘orphaned’ foreign keys
Domain integrity constraint
Rules specified for individual attributes
Data type, number of characters etc.
Validation rules
Bus 311: Fall 2003

5. Dependencies and Determinants
StateAbbrev functionally determines StatePopulation
StatePopulation is functionally determined by StateAbbrev
StateAbbrev is a determinant
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6. Determinants
Transitive Dependency
Partial Dependencies
StateAbbrev is a determinant for StatePopulation, StateBird, and BirdScientificName
CropName is a determinant for Exports
Quantity is functionally dependent on both StateAbbrev and CropName
StateBird is a determinant for BirdScientificName
Bus 311: Fall 2003

7. Problematic Dependencies
Partial Dependency
Funtional dependency on part of the primary key
Transitive Dependency
Functional dependency between two nonkey attributes
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8. Anomalies Insertion Anomaly Deletion Anomaly Update Anomaly
Can’t add row if don’t know part of primary key
Can’t add new client without knowing a ChildName
Deletion Anomaly
Delete data and unintentionally lose other critical data
Delete Client 8112, and lose all info on VetID 24
Update Anomaly
Change one attribute and changes must be made other places
Change ClientName for ClientID 4519, must change other record too
Bus 311: Fall 2003

9. Normalization
Process of bringing a relational database to an orderly form
Eliminate problems
Major process in database design
Many normal forms – we consider three
First Normal Form (1NF)
Second Normal Form (2NF)
Third Normal Form (3NF) – aka Boyce-Codd Normal Form (BCNF
Bus 311: Fall 2003

10. First Normal Form (1NF)
A relation is 1NF if it does not contain repeating groups
Process
Expand primary key to include primary key of repeating group – Independently for each repeating group
Create new relation (table) for each repeating group
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11. 1NF result Still problems
Insertion, deletion, and update anomalies in both relations
Caused by partial dependencies (next slide)
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12. Bus 311: Fall 2003

13. Second Normal Form (2NF)
A relation in 1NF is in 2NF if it does not contain any partial dependencies
Process
Identify functional depencies for each attribute
If necessary, create new relations to make each attribute functionally dependent on the entire primary key.
New relations should have primary keys that are subsets of the original composite key
A relation in 1NF with a single-attribute primary key is automatically in 2NF
Bus 311: Fall 2003

14. Result of converting to 2NF
Still problems?
Transitive dependency between VetID and VetName
All 3 anomalies exist in Client relation
3NF removes transitive dependencies
Bus 311: Fall 2003

15. Third Normal Form (3NF)
Boyce-Codd Normal Form (BCNF) is an improvement over original 3NF
A 2NF relation is in 3NF when there are no transitive dependencies
Process
Remove attributes that depend on the non-candidate-key (non-primary key)
Place in new relation with determinant as primary key
Bus 311: Fall 2003

16. Result of converting to 3NF
No data redundancy
No anomalies
Bus 311: Fall 2003

17. Exercises Gain a better understanding
Do Review Questions at end of RD appendix
RQ 1-6 will be on the exam!
RQ 7 will help you get a better understanding of how to apply to real-world situations
Some of RQ 8-14 are likely to be on the exam
If you do RQ 15-18, I will be happy to discuss your solution with you
Bus 311: Fall 2003