1
Chapter 2
Objectives: to understand
• Data modeling and why data models are
important
• The basic data-modeling building blocks
• What business rules are and how they influence
database design
• How the major data models evolved historically
• How data models can be classified by level of
abstraction
CS275 Fall 2010 1
Introduction to Data Modeling
• Data modeling reduces complexities of database
design
• Designers, programmers, and end users see data
in different ways
• Different views of same data lead to designs that
do not reflect organization’s operation
• Various degrees of data abstraction help
reconcile varying views of same data
CS275 Fall 2010 2
Data Modeling and Data Models
• Model: an abstraction of a real-world object or
event
– Useful in understanding complexities of the real-
world environment
• Data models
– Relatively simple representations of complex real-
world data structures
• Often graphical
• Creating a Data model is iterative and progressive
CS275 Fall 2010 3
The Importance of Data Models
• Facilitate interaction among the designer, the
applications programmer, and the end user
• End users have different views and needs for data
• Data model organizes data for various users
• Data model is a conceptual model - an abstraction
• It’s a graphical collection of logical constructs
representing the data structure and relationships
within the database.
– Cannot draw required data out of the data model
– An implementation model would represent how
the data are represented in the database.
CS275 Fall 2010 4
