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

Access, I have to solve a problem using access

I have to solve a problem using access

What is the error handling, What is the error handling Traditionally, b...

What is the error handling Traditionally, bits have been sent over line lacking any error correcting scheme in physical layer. The presence of the CPU in each modem makes it po

Sequential file organisation, Sequential File Organisation The most nec...

Sequential File Organisation The most necessary way to organise the collection of records in a file is to use sequential Organisation. Records of the file are stored in series

Column constraints-on delete cascade, CREATE TABLE prodtrans ( pno ...

CREATE TABLE prodtrans ( pno number (4) ptype char (1) CHECK (ptype in ('I','R','S')), qty number (5) FOREIGN KEY pno REFERENCES product (pno) ON DELETE CASCADE);

Explain retrieval in qbe, Explain retrieval in QBE? Retrieval in QBE : ...

Explain retrieval in QBE? Retrieval in QBE : A "GUI" for expressing queries. Based on the Domain Relational Calculus (DRC) Actually invented before GUIs. Very co

What is trigger, What is trigger Triggers are statements that are imple...

What is trigger Triggers are statements that are implemented automatically by the system as the side effect of a change to the database.

Draw an er diagram for organization of a student database, Draw an ER diagr...

Draw an ER diagram that shows the organization of a simple student database. The database captures the information about letter grades obtained by university students who enrolled

RDBMS, what is RDBMS? how it works? good example.

what is RDBMS? how it works? good example.

EER models, Ask question #MinimThe Georgia Tech Library (GTL) has approxima...

Ask question #MinimThe Georgia Tech Library (GTL) has approximately 16,000 members, 100,000 titles, and 250,000 volumes (an average of 2.5 copies per book). About 10 percent of the

Define functional and multivalued dependencies, Define functional and multi...

Define functional and multivalued dependencies.       Ans:  A functional dependency is a assets of the semantics of the attributes in a relation. The semantics point out how at

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