Generalization, Specialization and Aggregation in ER Model – GeneralizationGeneralization is a process of generalizing an entity which. Generalization Aggregation – Learn DBMS in simple and easy steps starting from its The reverse is called specialization where a person is a student, and that. Generalization Aggregation – The concept of generalization (specialization) is associated with special types of entities known as superclasses and subclasses, .
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The Enhanced ER Model As the complexity of data increased in the late s, it became more and more difficult to use the traditional ER Model for database modelling.
We use all the above features of ER-Model in order to create classes of objects in object-oriented programming. An entity type that includes one or more dissimilar sub-groupings of its occurrences that is required to be represented in a data model. Specialization is the abstracting procedure of acquainting new qualities with a current class of items to make one or all the more new classes of articles.
Specialization might be seen as the opposite procedure of Generalization. In this way, it is a base up methodology as two or lower lever substances are consolidated to shape a more elevated amount element. Specialization is opposite to Generalization. The concept of generalization specialization is associated with special types of entities known as superclasses and subclasses, and the process of attribute inheritance.
Conglomeration is the procedure of ordering data on an item, in this way abstracting a larger amount object.
The ER Model has the power of expressing database entities in a conceptual hierarchical manner. Aggregation does not change the meaning of navigation and routing across the relationship between the whole and its parts.
Generalization is a process of generalizing an entity which contains generalized attributes or properties of generalized entities.
Aggrfgation semantic data models have been proposed, and some of the most important semantic concepts have been successfully incorporated into the original ER model. ni
In this way, there are no ascribes particular to cruisers. As the complexity of data increased in the late s, it became more and wpecialization difficult to use the traditional ER Model for database modelling.
Hence, entities are combined to form a more generalised entity, in other words, sub-classes are combined to form a super-class. These properties are common in all persons, human beings. In basic terms, Generalization is a procedure of removing normal attributes from two or more classes and joining them into a summed up superclass.
Generalization is a Bottom up process.
Answered on 24th Jul,95 Views. Using aggregation we can express relationship among relationships. A distinct sub-grouping of occurrences of an entity type that require being represented in a data model. But in a company, persons can be identified as employee, employer, customer, or vendor, based on what role they play in the company.
Aggregration is a process when relation between two entities is treated as a single entity. Specjalization the hierarchy goes up, it generalizes the view of entities, and as we go deep in the hierarchy, it gives us the detail of every entity included. In generalization, the higher level entity can also combine with other lower level entities to make further higher level entity.
Since the s there has been a rapid amplification in the development of many new database systems that have more demanding database requirements than those of the traditional applications. The entity that is created will contain the common features. Another type of total says that it is abstracting a relationship in the middle of articles and survey the relationship as an item.
Hence, as part of the Enhanced ER Modelalong with other improvements, three new concepts were added to the existing ER Model, they were:. Inheritance is an important feature of Generalization and Specialization.
Generalization, Specialization and Aggregation in ER Model
In specialziation, some entities are accommodated together into one generalized entity or category based on their similar characteristics. Similarly, in a school database, persons can be specialized as teacher, student, or a staff, based on what role they play in school as entities.
As mentioned above, the process of generalizing entities, where the generalized entities contain the properties of all the generalized entities, is called generalization. Specialization is a process of identifying subsets of an entity that shares different characteristics.