DEFINITION : integrated collection of concepts, theories, axioms, contraints for description, organization, validation and interpretation of data.
USAGE : a fundamentals set of tools and methods to consistently & uniformty view, organize and tread database.
TYPE DATA MODEL :
OBJECT-BASED MODEL :
- Entity Relationship
- Object Oriented
Representation of data as an integrated collection of inter-related tables
Definition of tablesin relations data model, a tabled is viewed as a set of entities/object/record. each tabled is assigned a unique name.
A row (Called record or tuple) in a table represents an, entity, described by a set of common attributes.
Sample of relational data
A collumn in a table represents an attribute, or field that describes/characterizes an entity.
Domain of an Attribute
Domain of an attribute i (Donated D(i), is a set of all permissible value for the attribute i.reffering to table course of figure 1: