Database System Concepts
and
Architecture
(Module - 1 cont…)
Slide 2- 1
,Data Models
• Data Model:
• A set of concepts to describe the structure of a database, the
operations for manipulating these structures, and certain
constraints that the database should obey.
• Most data models also include a set of basic operations for
specifying retrievals and updates on the database.
• In addition to the basic operations provided by the data model,
it is becoming more common to include concepts in the data
model to specify the dynamic aspect or behavior of a database
application.
Slide 2- 2
,Data Models (continued)
• Data Model Operations:
• These operations are used for specifying database
retrievals and updates by referring to the constructs of
the data model.
• Operations on the data model may include basic model
operations (e.g. generic insert, delete, update) and user-
defined operations (e.g. compute_student_gpa,
update_inventory)
Slide 2- 3
, Categories of Data Models
• Conceptual (high-level, semantic) data models:
• Provide concepts that are close to the way many users
perceive data.
-(Also called entity-based or object-based data models.)
• Conceptual data models use concepts such as entities,
attributes, and relationships. (Entity Relationship Model)
• An entity represents a real-world object or concept, such as
an employee or a project from the miniworld that is
described in the database.
• Example…ER Model which includes entity, attributes and
relationships
• Physical (low-level, internal) data models:
• Provide concepts that describe details of how data is stored
Slide 2- 4
and
Architecture
(Module - 1 cont…)
Slide 2- 1
,Data Models
• Data Model:
• A set of concepts to describe the structure of a database, the
operations for manipulating these structures, and certain
constraints that the database should obey.
• Most data models also include a set of basic operations for
specifying retrievals and updates on the database.
• In addition to the basic operations provided by the data model,
it is becoming more common to include concepts in the data
model to specify the dynamic aspect or behavior of a database
application.
Slide 2- 2
,Data Models (continued)
• Data Model Operations:
• These operations are used for specifying database
retrievals and updates by referring to the constructs of
the data model.
• Operations on the data model may include basic model
operations (e.g. generic insert, delete, update) and user-
defined operations (e.g. compute_student_gpa,
update_inventory)
Slide 2- 3
, Categories of Data Models
• Conceptual (high-level, semantic) data models:
• Provide concepts that are close to the way many users
perceive data.
-(Also called entity-based or object-based data models.)
• Conceptual data models use concepts such as entities,
attributes, and relationships. (Entity Relationship Model)
• An entity represents a real-world object or concept, such as
an employee or a project from the miniworld that is
described in the database.
• Example…ER Model which includes entity, attributes and
relationships
• Physical (low-level, internal) data models:
• Provide concepts that describe details of how data is stored
Slide 2- 4
