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

Assignments, i have assignments I don''t have time to finish because of wo...

i have assignments I don''t have time to finish because of work and other assignments, can you help with this? All are from the book Darabase design, application development and a

Functional dependencies, CAR SALE (Car_id, Option_type, Option_listprice, S...

CAR SALE (Car_id, Option_type, Option_listprice, Sale_date, Option_discountedprice) This relation refers to options installed in cars (e.g., cruise control) that were sold at a de

Entity relationship diagram, Ask questApollo Hospitals (AH) is a popular me...

Ask questApollo Hospitals (AH) is a popular medical service provider in Oman. AH wants to automate its business functions into an information system. The proposed information syst

Explain the term- data flows, Explain the term- Data Flows Data Flows:...

Explain the term- Data Flows Data Flows: A data flow connects output of an object or process to input of another process or object. It represents an in-between data value wit

Represent the form as a relational schema, Question: This form represen...

Question: This form represents one of a number used for each sailing of a range of boats. A passenger may go on many sailings and will have the same passenger number for each.

Explain the terms data warehousing and data mining, Question: i) Explai...

Question: i) Explain the terms data warehousing and data mining. ii) Discuss the importance of the following security principles that a digital firm should amongst others, n

What is relational calculus, What is Relational calculus? Relational c...

What is Relational calculus? Relational calculus is a Non- Procedural language.

Chapter 1 - Profile for the Organization, Chapter 1 - Profile for the Organ...

Chapter 1 - Profile for the Organization You have to select an organization of your choice and assume that you work for that organization. Now you must prepare a brief profile of t

Shared lock or read lock, Shared lock or Read Lock It is requested ...

Shared lock or Read Lock It is requested by a transaction that needs to just read the value of data item. A shared lock on a data item does not permit an exclusive lock

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