Object Based Data Models

ER Model

Object Based Data Models-

Object base data model is used for describing hows data in stored in database and hows they connected with each other. In object based data model the object or entities are connected with each other for sharing data between one another. Entities are connected other entities. Object based data model are used in real world for indicating a database or entity relationship between each other.

Some examples/types of object based data model is as fallows-

  1. Entity Relationship Data Model
  2. Object Oriented Data Model
  3. Semantic Data Model
  4. Functional Data Model

In that example or type the entity relationship data model and object oriented data model is more popular.

Entity Relationship Data Model-

Entity relationship model is most popular model for indicating a project work. In entity relationship model consist of entities, attribute and relationships for describing ER model.In ER model Entity defines a name of any place, thing or important fact about industry or project and they indicating as rectangle. Attribute is a extra information about entity,they defines the characteristics of that entity clearly. Relation defines the relationship between two entities with each other.


ERM symbols


Example-In hospital management system Doctor, Patient, Department is an entity of hospital management system. The Doctor_id, Doctor_name, Doctor_mobileno is an attributes of Doctor entity mainly.


In ER model use primary key and foreign key indication also.


In ER model cardinalities play a important role for indicating hows entities are relate with other entities. It indicating a relation of entities in form of –

  1. ONE:ONE-(1:1)
  2. ONE:MANY-(1:M)
  3. MANY:MANY-(M:M)
  4. MANY:ONE-(M:O)

If one entity interact with another entity as once for getting their value then that cardinality indicating as ONE:ONE relationship. The cardinalities are denoted the hows entities associated with another entity.


In Diagram shows Teacher and Student is a Entity and S_id, S_name is an attributes of students.the cardinalities also describe in ER Model diagram.



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