E-R model -:-
Is a data model ,which is very closed to the real word & can easily be reduce into relational form .It is easy to simulate things in a real word enviornment . E-R model is represent by E-R diagram and E-R diagram is a fictorial or graphical representation of a real word scenario.
=> following are the components of entity relation diagram
1) Entity Set :- A real word object is called an entity and similar types of entity are collectivilly called an entity set.
2) Attribute :- Every entity set as a set of common properties , these properties are called attributes.
3) Domain :- Domain indicate a set of permissable of allow values for an attributes.
4) Relationship :- different entity set have different types of relationship.
Notation of E- R diagram :-----------------
No comments:
Post a Comment