Project Report of Electricity Billing System
Page - 33
Model is an abstraction process that hides super details while
highlighting details relation to application at end.
A data model is a mechanism that provides this abstraction for database
application.
Data modeling is used for representing entities and their relationship in the
database.
Entities are the basic units used in modeling database entities can have
concrete existence or constitute ideas or concepts.
Entity type or entity set is a group of similar objects concern to an
organization for which it maintain data,
Properties are characteristics of an entity also called as attributes.
A key is a single attribute or combination of 2 or more attributes of an
entity set is used to identify one or more instances of the set.
In relational model we represent the entity by a relation and use tuples to
represent an instance of the entity.
Relationship is used in data modeling to represent in association between
an entity set.
An association between two attributes indicates that the values of the
associated attributes are independent.
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