Additional Features of the ER Model : | Readstall

Additional Features of the ER Model :

13-12-18 Gudditi Naganjaneyulu 0 comment

Additional Features of the ER Model :

Er model allows us to the describe some properties of the data .additional features of er model are as fallows :

  • Generalization
  • Specialization
  • Aggregation
  • Inheritance

Generalization:

Generalization consists of identifying the some common characteristics of a collection of entity sets creating a new entity

The process of generalization entities where the similar set of entities contains the common properties of all the generalized entities 

Specialization:

Specialization is the process of identifying subsets of an entity set shares common distinguish ch raters .

An entity set might contains distinct subgroups of entities typically the super class has defines first ,next the subgroups of entities typically the super class has defines first ,next the sub class are defines ,sub class –specifies attribute and relationships sets . we can  “ISA” Relationship to represent specialization

Ex : take a group  people

Aggregation: 

Aggregation is an abstraction in which relationship sets are treated as higher level entity set.aggregation allows us to indicated that relationship set participants in another relationship set

Inheritance:

Inheritance is an important feature of generalization and specialization .it allows low-level entities to inherit the attributes of high level entities .

 



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