DATA MODELING BASICS - Database Design and Development: An Essential Guide for IT Professionals - page 150

Plan / Feasibility Requirements Defn. Design Implementation

Semantic
Data Model

Conventional
Data Model

Schema
Level Model

Physical
Data Model

Figure 5-8 Data modeling in DDLC.

Real-world
Information

Semantic
Data Model

Conventional
Data Model

Schema
Level Model

Physical
Data Model

Real-world
=

Model
capturing the
correct and
true meanings
of reality

Evolved data
models such
as
=

Schema and
subschema
definitions
using DDL

Physical
data in
files and
records

“things”
= associations
= rules
= constraints

hierarchical

network
= relational

=

= object-
based data
model
= entity-
relationship
(E-R) data
model

SPECIFIC DBMS

Figure 5-9 Data models at different levels.

PATTERNS OF DATA MODELING

At this point, two aspects of data modeling call for your attention. First, you realize
the importance of data modeling in the database development process. You know
the benefits and understand the reasons for creating a data model. You need to be
clear about the purpose and the place of data modeling in the development life
cycle. Second, you need to grasp the essential differences between the patterns of
data models mentioned in our discussion.
Figure 5-9 distinguishes the placement of the types of data models at different
levels.