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Contents
Chapter 1: Introduction	9
Data Modeling Concepts .........................................................................	9
Benefits of Data Modeling ........................................................................	9
Methods......................................................................................	10
Typographical Conventions ......................................................................	10
Chapter 2: Information Systems, Databases, and Models	11
Introduction...................................................................................	11
Data Modeling .............................................................................	11
Data Modeling Sessions .........................................................................	13
Session Roles ..............................................................................	14
Sample IDEF1X Modeling Methodology ............................................................	15
Modeling Architecture ..........................................................................	16
Logical Models.................................................................................	16
Entity Relationship Diagram ..................................................................	17
Key-Based Model ...........................................................................	17
Fully-Attributed Model ......................................................................	17
Physical Models................................................................................	17
Transformation Model ......................................................................	18
DBMS Model ..............................................................................	18
Chapter 3: Logical Models	19
How to Construct a Logical Model .................................................................	19
Entity Relationship Diagram ......................................................................	20
Entities and Attributes Defined ...............................................................	20
Logical Relationships ........................................................................	22
Many-to-Many Relationships .................................................................	23
Logical Model Design Validation ..................................................................	24
Data Model Example............................................................................	25
Chapter 4: The Key-Based Data Model	27
Key-Based Data Model ..........................................................................	27
Key Types .....................................................................................	28
Entity and Non-Key Areas ....................................................................	28
Primary Key Selection ...........................................................................	28
	Contents 5

Alternate Key Attributes .........................................................................	30
Inversion Entry Attributes .......................................................................	31
Relationships and Foreign Key Attributes ...........................................................	31
Dependent and Independent Entities ..........................................................	32
Identifying Relationships.....................................................................	33
Non-Identifying Relationships ................................................................	34
Rolenames ................................................................................	35
Chapter 5: Naming and Defining Entities and Attributes	37
Overview .....................................................................................	37
Entity and Attribute Names ......................................................................	37
Synonyms, Homonyms, and Aliases ............................................................	38
Entity Definitions...............................................................................	39
Descriptions ...............................................................................	40
Definition References and Circularity ..........................................................	41
Business Glossary Construction ...............................................................	41
Attribute Definitions ............................................................................	42
Validation Rules ............................................................................	42
Rolenames ....................................................................................	43
Definitions and Business Rules....................................................................	44
Chapter 6: Model Relationships	47
Relationships ..................................................................................	47
Relationship Cardinality .........................................................................	48
Cardinality in Non-Identifying Relationships .....................................................	50
Referential Integrity ............................................................................	51
Referential Integrity Options .................................................................	52
RI, Cardinality, and Identifying Relationships ....................................................	54
RI, Cardinality, and Non-Identifying Relationships ................................................	55
Additional Relationship Types ....................................................................	56
Many-to-Many Relationships .................................................................	56
N-ary Relationships .........................................................................	58
Recursive Relationships......................................................................	60
Subtype Relationships .......................................................................	62
Complete Compared to Incomplete Subtype Structures ...........................................	64
Inclusive and Exclusive Relationships...........................................................	65
IDEF1X and IE Subtype Notation...............................................................	65
When to Create a Subtype Relationship ........................................................	66

6 Methods Guide

Chapter 7: Normalization Problems and Solutions	67
Normalization .................................................................................	67
Overview of the Normal Forms ...................................................................	68
Common Design Problems .......................................................................	69
Repeating Data Groups ......................................................................	69
Multiple Use of the Same Attribute ............................................................	71
Multiple Occurrences of the Same Fact .........................................................	73
Conflicting Facts............................................................................	74
Derived Attributes ..........................................................................	76
Missing Information ........................................................................	77
Unification ....................................................................................	79
How Much Normalization Is Enough ...............................................................	80
Support for Normalization .......................................................................	82
First Normal Form Support ...................................................................	82
Second and Third Normal Form Support ........................................................	83
Chapter 8: Physical Models	85
Objective .....................................................................................	85
Support for the Roles of the Physical Model.........................................................	86
Summary of Logical and Physical Model Components .............................................	86
Denormalization ...............................................................................	87
Appendix A: Dependent Entity Types	89
Classification of Dependent Entities ...............................................................	89
Glossary	91
Index	95

Contents 7

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