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, .
|Genre:||Health and Food|
|Published (Last):||18 April 2005|
|PDF File Size:||6.3 Mb|
|ePub File Size:||11.63 Mb|
|Price:||Free* [*Free Regsitration Required]|
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’. Aggregation genera,ization not change the meaning of navigation and routing across the relationship between the whole and its parts.
It’s more like Superclass and Subclass system, but the only difference is the approach, which is bottom-up. In this way, there are no ascribes particular to cruisers. Using aggregation we can express relationship among relationships.
But in a company, persons can be identified as employee, employer, customer, or vendor, based on what role they play in the company. It breaks an entity into multiple entities from higher level super class to lower level sub class.
The ER Model has the capability of articulating database grneralization in a conceptual hierarchical manner.
In this way, it is a base up methodology as two or lower lever substances are consolidated to shape a more elevated amount element. Comments Edit Question Edit Categories. A person has name, date of spcialization, gender, etc.
Hence some improvements or enhancements were made to the existing ER Model to make it able to handle the complex applications better. Specialization is opposite to Generalization.
In simple terms, Aggregation is a process when relation between two entities is treated as a single entity. 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 concept of generalization specialization is associated with special types of entities known as superclasses and subclasses, and the process of attribute inheritance. As mentioned above, the process of generalizing entities, where the generalized entities contain the properties of all the generalized entities, is called generalization.
For example, a particular student speckalization Mira can be generalized along with all the students.
Generalization, Specialization and Aggregation in ER Model | Studytonight
This special kind of relationship is termed as an aggregation. Aggregation in DBMS Conglomeration is the procedure of ordering data on an item, in this way abstracting a larger amount object.
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 their disparities. 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.
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. So it is a top-down methodology in which one larger amount substance can be separated into two lower level element.
Inheritance is an important feature of Generalization and Specialization. Answered on 24th Jul,95 Views. C Tutorials C Programs. Conglomeration is the procedure of ordering data on an item, in this way abstracting a larger amount object.
Going up in this structure is called generalizationwhere entities are clubbed together to represent a more generalized view. Generalization is a process of generalizing an entity which contains generalized attributes or properties of generalized entities. A generalization is a bottom-up approach. Aggregation represents relationship between a whole object and its component.
An entity type that includes one or more dissimilar sub-groupings of its occurrences that is required to be represented in a data model. Generalization Generalization is a bottom-up approach in which two lower level entities combine to form a higher level entity. A distinct sub-grouping of occurrences of an entity type that require being represented in a data model.
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. Such an entity-set is treated in the same manner as any other entity-set. In basic terms, Generalization is a procedure of removing normal attributes from two or more classes and joining them into a summed up superclass. Specialization might be seen as the opposite procedure of Generalization.
Generalization, Specialization and Aggregation in ER Model
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. For example, the attributes of a Person class such as name, age, and gender can be inherited by lower-level entities such as Student or Teacher.
Various semantic data models have been proposed, and some of the most important semantic concepts have been successfully incorporated into the original ER model. Comments Edit Answer Report. In basic terms, a gathering of substances in specialization can be classified into sub-bunches in view of their attributes.
The reverse is called specialization where a person is a student, and that student is Mira.
Hence, as part of the Enhanced ER Modelalong with other improvements, three new concepts were added to the existing ER Model, they were: Another type of total says that it is abstracting a relationship in the middle of articles and survey the relationship generaliztion an item. The details of entities are generally hidden from the user; this process known as abstraction.
It is a form of abstraction that specifies two or more gsneralization sub class having common characters that can be generalized into one single entity super class at higher level hiding all the differences. Going up in this structure is called generalization, where entities are associated together to represent a more generalized view. In specialization, a group of entities is divided into generwlization based on their characteristics. Specialization is the opposite of generalization.
It is a top down approach in which we first define the super class and then sub class and then their attributes and relationships. In this way, the two deliberation instruments used to model data: