1. Database Architecture Normalization

2. Purpose of Normalization A technique for producing a set of relations with desirable properties, given the data requirements for an enterprise. First developed by E.F. Codd Performed as “tests” on a relation to determine whether it satisfies or violates the requirements for a given normal form.

3. Data Redundancy & Update Anomalies The problem of data redundancy Insertion anomalies Deletion anomalies Update or Modification anomalies

4. Unnormalized Form (UNF) ID_NoNameAddressPhone 001John Smith123 Maple Street909-555-1212 001Susan Brown456 Pine Avenue404-555-1234

5. Unnormalized Form (UNF) ID_NoNameAddressPhone 001John Smith123 Maple Street909-555-1212 001Susan Brown456 Pine Avenue404-555-1234

6. Unnormalized Form (UNF) ID_NoNameAddressPhone 001John Smith123 Maple Street909-555-1212 001Susan Brown456 Pine Avenue404-555-1234

7. First Normal Form (1NF) First Normal Form (1NF) – a relation in which the intersection of each row and column contains one and only one value. Atomic level attributes. No repeating groups Unique key for the table

8. Characteristics of Functional Dependencies A Functional Dependency (FD) describes the relationship between attributes in a relation. For example, if A and B are attributes of relation R, B is functionally dependent on A if each value of A is associated with exactly one value of B.

9. The Process of Normalization A “decomposition” process Relation

10. Functional Dependencies X → Y Stated as “X implies Y”, or “Y is functionally dependent on X” X is defined as the “determinant”

11. Functional Dependency AB → CDEFG

12. Functional Dependency AB → CDEFG The problem is a partial dependency….a non-determinant attribute is dependent on only one determinant attribute in a composite key.

13. Functional Dependency AB → CDEFG Decomposition resolves the problem…… R 1 (A CDFG) R 2 (B E)

14. Second Normal Form (2NF) Must be in 1NF No Partial Dependencies

15. Functional Dependency AB → CDEFG

16. Functional Dependency AB → CDEFG The problem is a transitive dependency….a non-determinant attribute is dependent on another non-determinant attribute.

17. Functional Dependency AB → CDEFG Decomposition resolves the problem…… R 1 (AB CEF) R 2 (D G)

18. Third Normal Form (3NF) Must be in 2NF No transitive dependencies

19. BCNF AB → CDEFG

20. Normalization recap Un-normalized data 1NF 2NF 3NF BCNF

21. Questions?