The Relational Model and Normalization Database Processing Chapter 5 The Relational Model and Normalization David M. Kroenke © 2000 Prentice Hall

The Relational Model Broad, flexible model Basis for almost all DBMS products E.F. Codd defined well-structured “normal forms” of relations, “normalization” Page 113

Relation Two-dimensional table Rows are tuples Columns are attributes Page 113

Equivalent Relational Terms Page 114 Figure 5-1 © 2000 Prentice Hall

Functional Dependency “relationship between or among attributes” Page 114 Figure 5-2 © 2000 Prentice Hall

Functional Dependency Notation SID  Major ComputerSerialNumber  MemorySize (SID, ClassName)  Grade Page 115

Key “a group of one or more attributes that uniquely identifies a row” Page 116 Figure 5-3 © 2000 Prentice Hall

Combination Key Page 117 Figure 5-4 © 2000 Prentice Hall

Normalization “the process of evaluating and converting a relation to reduce modification anomalies” Page 118

Anomaly “an undesirable consequence of data modification in which two or more different themes are entered (insertion anomaly) in a single row or two or more themes are lost if the row is deleted (deletion anomaly)” Page 118

Normal Forms “classes of relations and techniques for preventing anomalies” DK/NF = Domain Key Normal Form (free of modification anomalies) Page 118

First Normal Form “any table of data that meets the definition of a relation” Figure 5-3 © 2000 Prentice Hall

Second Normal Form “when all of a relation’s nonkey attributes are dependent on all of the key” Figure 5-5 © 2000 Prentice Hall

Third Normal Form “if it is in second normal form and has no transitive dependencies” Figure 5-7 © 2000 Prentice Hall

Boyce-Codd Normal Form “if every determinant is a candidate key” Figure 5-8 © 2000 Prentice Hall

Fourth Normal Form “if in BCNF and has no multi-value dependencies” Figure 5-11 © 2000 Prentice Hall

Fifth Normal Form ? Page 125

Domain Key Normal Form “if every constraint on the relation is a logical consequence of the definition of keys and domains” Page 125

DK/NF Terms Constraint “a rule governing static values of attributes” Key “unique identifier of a tuple” Domain “description of an attribute’s allowed values” Page 126

DK/NF Example Figure 5-13 © 2000 Prentice Hall

DK/NF Example Figure 5-15 © 2000 Prentice Hall

DK/NF Example Figure 5-16 © 2000 Prentice Hall

Summary of Normal Forms Figure 5-18 © 2000 Prentice Hall

A  B relationships A  B and B  A one-to-one A  B but B not  A many-to-one A not  B and B not  A many-to-many Page 131

Summary of Relationships Figure 5-19 © 2000 Prentice Hall

Optimization De-Normalization Controlled Redundancy Page 135