Define the concept of aggregation, Database Management System

Assignment Help:

Define the concept of aggregation.  Give two examples where this concept is useful.

Ans: Aggregation transforms a relationship among the objects into a higher-level object. A new data type known as aggregate is developed which, under specific criteria of "well-definedness," defines aggregation abstractions. Relational databases illustrated as collections of aggregates are structured like a hierarchy of n-ary relations. To keep well-definedness, update operations on such type of databases must keep two invariants. Well-defined relations are different from relations in third normal form. It is displayed that these notions are complementary and both are significant in database design. A top-down method for database design is described that separates decisions concerning aggregate structure from decisions concerning key identification. It is suggested that aggregate types, and other sorts which support real-world abstractions with no introducing Key identification.


Related Discussions:- Define the concept of aggregation

Prepare a data flow diagram for computing the volume, Prepare a data flow d...

Prepare a data flow diagram for computing the volume and surface area of a cylinder. Inputs are the height and radius of the cylinder. Outputs are the volume and surface area of th

Single valued normalisation, Single Valued Normalisation  Codd in the y...

Single Valued Normalisation  Codd in the year 1972 formed three normal forms (1NF, 2NF, and 3NF). These were based on functional dependencies between the attributes of a relati

Er diagrams, in an organization several projects are undertaken. Each proje...

in an organization several projects are undertaken. Each project can employ one or more employees. Each employee can work on one or more projects. Each project is undertaken on the

What is deadlock, What is deadlock? How can it be avoided? How can it be re...

What is deadlock? How can it be avoided? How can it be resolved once it occurs? Deadlock happens when two transactions are each waiting on a resource that the other transaction

Relational database, Consider the following relational database: STUDENT (n...

Consider the following relational database: STUDENT (name, student#, class, major) COURSE (course name, course#, credit hours, department) SECTION (section identifier, course#, sem

State the terms designing the database and normalization, State the terms D...

State the terms Designing the database and Normalization Designing the database: Out of the ERD we have formed, it is very easy to verify the tables, the attributes which the

Decompose the table with the functional dependencies, Decompose the table w...

Decompose the table with the following description and functional dependencies into a set of equivalent tables normalized to 3NF or BCNF. This database stores records from a (ve

The advantages of a database management system, The advantages of a databas...

The advantages of a database management system (DBMS) include :- Data integrity and elimination of duplication.

Differentiate sub-class and super-class, Differentiate sub-class and super-...

Differentiate sub-class and super-class? The specialization of a class is known as subclasses.eg: employee is a subclass of person and teller is a subclass of employee. Convers

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd