lecture

Data Model
Is a relatively simple representation, usually graphical, of more abstraction of a more complex real- world object event, a data model represents data structures and their characteristics , relations , constraints , transformations , and , other constructs with purpose of supporting a specific problem domain .

The Importance of Data Models
Data models can facilitate interaction among the designer, the applications programmer, and the end user, a well- developed data model can even faster improved understanding of the organization for which the database design is developed.


Data Model Basic Building Blokes

Entity: is anything (a person, a please, a thing, or an event) about which data are to be collected and stored. An entity represents a particular type of object in the real world entities are "distinguishable" that is each entity occurrence is unique and distinct. For example, a CUSTOMER entity would have many distinguishable customer occurrences such as Ahmed, Ali, etc.

Attribute: is a characteristic of an entity. For example, a CUSTOMER entity would be described by a attributes such as customer last name, customer first name, its equivalent of fields in the file systems