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Sarabjit Kumar, Lovely Professional University Unit 14: Data Modeling

Unit 14: Data Modeling Notes

CONTENTS
Objectives
Introduction

14.1 Data Models
14.2 Data Objects
14.3 Attribute

14.4 Relationships and Relationship Set
14.5 Cardinality and Modality
14.6 Summary
14.7 Keywords
14.8 Review Questions

14.9 Further Readings

Objectives

After studying this unit, you will be able to:

Recognize the Data Modeling concepts
Describe Data Objects
Explain Data Attributes
Discuss Relationships
Scan Cardinality and Modality

Introduction

A data model is not just a way of structuring data: it also defines a set of operations that can be
performed on the data. The relational model, for example, defines operations such as select,
project, and join. Although these operations may not be explicit in a particular query language,
they provide the foundation on which a query language is built.

Example: Databases include word processors, dictionary, mail merges, user preferences
and information management systems.

Various techniques are used to model data structure. Most database systems are built around
one particular data model, although it is increasingly common for products to offer support for
more than one model. For any one logical model various physical implementations may be
possible, and most products will offer the user some level of control in tuning the physical
implementation, since the choices that are made have a significant effect on performance.
An example of this is the relational model: all serious implementations of the relational model
allow the creation of indexes which provide fast access to rows in a table if the values of certain
columns are known.

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