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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. Terms such as superclass, subclass, or inheritance come to mind when thinking about the object-oriented approach. These concepts are very important when. Speculation Specialization and Aggregation in DBMS are deliberation systems used to model data. The reflection is the instrument used to shroud the.

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To illustrate the need for such a construct, quaternary relationships are used which lead to redundancy in data storage.

The reverse is called specialization where a person is a student, generalizatiion that student is Mira. The generalizatiom of entities are generally hidden from the user; this process known as abstraction. In basic terms, Generalization is a procedure of removing normal attributes from two or more classes and joining them into a summed up superclass.

Aggregation represents relationship between a whole object and its component. Aggregation One limitation of the E-R model is that it cannot express relationships among relationships.

Below is the example of aggregation relation between offer which is binary relation between center and course and visitor. The entity that is created will contain the common features. The entity shall be generaoization student, and further, the student is a person. It breaks an entity into multiple entities from higher level super class to lower level sub class.

It’s more like Superclass and Subclass system, but the only difference is the approach, which is bottom-up. On the basis of the commonalities, generalization synthesizes these entity sets into a single, higher-level entity set. Conglomeration is the procedure of ordering data on an item, in this way abstracting a larger amount object. 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.

Explain Generalization, Specialization & Aggregation with the help of an example

This special kind of relationship is termed as an aggregation. 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.


Aggregatio get question papers, syllabus, subject analysis, answers – all in one app. Such an entity-set is treated in the same manner as any other entity-set.

For example, a particular student named Mira can be generalized along with all the students. In specialization, a group of entities is divided into sub-groups based on their characteristics.

Comments Edit Question Edit Categories. In generalization, a number of entities are brought together into one generalized entity based on their similar characteristics.

Generalization, Specialization and Aggregation Concepts in DBMS

In specialization, a higher level entity may not have any lower-level entity sets, it’s possible. In generalization, the higher level entity can also combine with other lower level entities to make further higher level entity.

Generalization is a bottom-up approach in which two lower level entities combine to form a higher level entity. Generalization It is a bottom-up approach in which two lower level entities combine to form higher entity. Aggregation in DBMS Conglomeration is the procedure of ordering data on an item, in this way abstracting a larger amount object.

In generalization, some entities are accommodated together into one generalized entity or category based on their similar characteristics.

So it is a top-down methodology in which one larger amount substance can be separated into two lower level element.

Specialization It is opposite to Generalization. Hence, entities are combined to form a more generalised entity, in other words, sub-classes are combined to form a super-class.

As the basic concepts of ER modeling are often not geenralization to represent the requirements of the newer complex applications which therefore stimulated the need to develop additional ‘semantic’ modeling concepts. Answered on 24th Jul,95 Views. Generalization is used to emphasize the similarities among lower-level entity sets and to hide the differences in the schema. In this way, the two deliberation instruments used to model data: In the diagram above, the relationship between Center and Course together, is acting as an Entity, which is in relationship with another generaliation Visitor.

An example of aggregation is the ‘Teacher’ entity following the ‘syllabus’ entity act as a single entity in the relationship. It is a top down approach in which we first define the super class and then sub class and then their attributes speciailzation relationships. The reflection is the instrument abgregation to shroud the unnecessary points of interest aggreyation an arrangement of articles.


The normal qualities implies here properties or techniques. Generalization Specialization Aggregration Let’s understand what they are, and why were they added to the existing ER Model. JavaScript Tutorials jQuery Tutorials. The best way to mode such situations is to use aggregation.

Generalization, Specialization and Aggregation in ER Model

It is a top-down approach in which one higher level entity can be broken down into two lower level entity. A distinct sub-grouping of occurrences of an entity type that require being represented in a data model. For example, Saving and Current account types entities can be generalised and an entity with name Account can be created, which covers both. Aggregation does not change the meaning of navigation and routing across the relationship between the whole and its parts.

In basic terms, a gathering of substances in specialization can be classified into sub-bunches in view of their attributes.

Generalization, Specialization and Aggregation in DBMS

The relationship between a superclass and a subclass is one-to-one 1: Speculation is an abstracting procedure of review sets of items as a solitary general class by focusing on the general attributes of the constituent sets while stifling or overlooking speialization disparities.

Going up in this structure is called generalizationwhere entities are clubbed together to represent a more generalized view. Sppecialization ER Model has the power jn expressing database entities in a conceptual hierarchical manner. The concept of generalization specialization is associated with special types of entities known as superclasses and subclasses, and the process of attribute inheritance.

It is a form of abstraction that specifies two or more entities sub class having common characters that can be generalized into one single entity super class at higher level hiding all the differences.