GENERALIZATION SPECIALIZATION AGGREGATION IN DBMS PDF

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, .

Author: Vikasa Nahn
Country: Chad
Language: English (Spanish)
Genre: Health and Food
Published (Last): 28 September 2011
Pages: 256
PDF File Size: 2.93 Mb
ePub File Size: 3.64 Mb
ISBN: 864-8-38902-996-2
Downloads: 2227
Price: Free* [*Free Regsitration Required]
Uploader: Tojalar

Genefalization the complexity of data increased in the late s, it became more and more difficult to use the traditional ER Model for database modelling.

So it is a top-down methodology in which one larger amount substance can be separated into two lower level element. Comments Edit Answer Report. Similarly, in a school database, persons can be specialized as teacher, student, or a staff, based on what role they play aggregqtion school as entities. 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.

The Enhanced ER Model

The concept of generalization specialization is associated with special types of entities known as superclasses specia,ization subclasses, and the process of attribute inheritance. The relationship between a superclass and a subclass is one-to-one 1: As 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.

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 opposite to Generalization. Going up in this structure is called generalizationwhere entities are clubbed together to represent a more generalized view.

Generalization Aggregation

C Tutorials C Programs. Another type of total says that it is abstracting a relationship in the middle of articles and survey the relationship as an item.

  BRUCE ALBERTS BIOLOGIA MOLECULAR DE LA CELULA 5TA EDICION PDF

Aggregation does not change the meaning of navigation and routing across the relationship between the whole and its parts. It breaks an entity into multiple entities from higher level super class to lower level sub class. Aggregration is a process when relation between two entities is treated as a single entity. For example, a particular student named Mira can be generalized along with all the students. An example of aggregation is the ‘Teacher’ entity following the ‘syllabus’ entity act as a single entity in the dbmd.

Specialization might be seen as the opposite procedure of Generalization.

In this chapter, you will learn about the main two important concepts. A distinct sub-grouping of occurrences of an entity type that require being represented in a data model.

As the basic concepts of ER modeling are often not enough to represent the requirements of the newer complex applications epecialization therefore stimulated the need to develop additional ‘semantic’ modeling concepts.

Various semantic data models have been proposed, and some of the most important semantic concepts have been successfully incorporated into the original ER model. Specialization is a process of identifying subsets of an entity that shares different characteristics. Responsive Theme powered by WordPress. In simple terms, Aggregation is a process when relation between two entities is treated as a single entity.

For example, Saving and Current account types entities can be specualization and an entity with name Account can be created, which covers both. 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 xbms all the differences.

Generalization, Specialization and Aggregation in ER Model

Generalization is a Bottom up process. Hence, as part of specializstion Enhanced ER Modelalong with other improvements, three new concepts were added to the existing ER Model, they were:. These properties are common in all persons, human beings. Hence, as part of the Enhanced ER Modelalong with other improvements, three new concepts were added to the specializaton ER Model, they were: Would you like to add a better answer?

  LAJJA SHAME PDF

The reflection is the instrument used to shroud the unnecessary points of interest of an arrangement of articles. JavaScript Tutorials jQuery Tutorials. In generalization, a number of entities are brought together into one generalized entity based on their similar characteristics.

A relationship represents a connection between two entity types that are aggregaiton at the same level.

As the hierarchy goes up, it generalizes the view of entities, and as you go deep in the hierarchy, it will provide with the detail of every entity included. Inheritance is an important feature of Generalization and Specialization. An entity type that includes one or more dissimilar sub-groupings of its occurrences that is required to be 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. Sometimes you may want to model a ‘has-a,’ ‘is-a’ or ‘is-part-of’ relationship, in which one entity represents a larger entity the ‘whole’ that will consist of smaller entities the ‘parts’.

We use all the above features of ER-Model in order to create classes of objects in object-oriented programming. The entity shall be a student, and further, the student is a person. The ER Model has the capability of articulating database entities in a conceptual hierarchical manner. Comments Edit Question Edit Categories. Such an entity-set is treated in the same manner as any other entity-set.

It allows lower-level entities to inherit the attributes of higher-level entities. 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 normal qualities implies here properties or techniques.