DBDI 30/05 /2007
Lecture 2 /CDM 1
DBDI / Lecture 2
Conceptual Data Modeling
Dr. Ala Al-Zobaidie
The slides are based on the textbooks
Database Systems by Connolly & Begg &
Fundamentals of Database Systems by Elmasri & Navathe
30/05/2007 Lecture 2 2
Lecture’s Objectives
• System Development & Conceptual Data Model
• Entity-Relationship Model concepts
– Entity types
– Attributes
– Relationship types
– Attributes on relationship
– Structural Constraints (Cardinality & Participation)
• Extended case studies
• Problems with ER Models
• The Enhanced E-R Model
– Super-classes & Subclasses of Entity Type
– Attribute Inheritance
– Specialization & Generalization and their Constraints.
• Further Case Studies with different ERD notations
30/05/2007 Lecture 2 3
Systems Development techniques
• There are many different techniques available to
help you with the tasks of systems development.
• Fall into three categories:
1. Functions
Modeling
2. Information
Modeling,
3. Cross
Referencing
which involves
modeling the
links between
Information
30/05/2007 Lecture 2 4
Conceptual, Logical & Physical Models
/1
• Information & process modeling usually carried-
out separately and cross-checked.
• Development result is kept in an operational
Database & applications can access it.
30/05/2007 Lecture 2 5
Conceptual, Logical & Physical Models
/2
• Conceptual:
– Develop formal models of the bu siness information & process
requirements.
• Logical:
– Transform the Conceptual Mode ls into definitions for the technical
environment
Physical Build phase:
–you develop and
run Structured
Query Language
(SQL)
statements to
create the
physical
database objects
30/05/2007 Lecture 2 6
Data Modeling, ERD /1
• Attempt to provide a representation of
(user) reality
• Ignores some of the complexity of the real world
• Simplicity attained by using small set of constructs
• Attempt to reduce the organisation’s world
into a description of entities and
relationships
• Simple description of information requirements that
can be used by the computer
