Extended e-r features, Database Management System

Assignment Help:

Although, the essential features of E-R diagrams are enough to design many database situations. Though, with more difficult relations and advanced database applications, it is need to move to enhanced features of E-R models. The three such features are:

  • Generalisation
  • Specialisation, and
  • Aggregation

In this part, we have described them with the help of an example. More detail on them are available in the further readings and MCS-043.

Example: A bank has an account entity set. The accounts of the bank can be of two parts:

  • Savings account
  • Current account

The statement as above shows a specialisation/generalisation hierarchy. It can be shown as

1135_Extended E-R features.png

Figure: Generalisation and Specialisation hierarchy


Related Discussions:- Extended e-r features

ER diagram, #question. acompani datdbase needs to store information about e...

#question. acompani datdbase needs to store information about employees (identified by a social security number,with salary and phone as attributes) and departments (identified by

Define canonical cover, Define canonical cover? A canonical cover Fc fo...

Define canonical cover? A canonical cover Fc for F is a set of dependencies like F logically implies all dependencies in FC and Fc logically shows all dependencies in F.

Give concurrent sub states diagram for the classroom, Give Concurrent sub s...

Give Concurrent sub states diagram for the classroom and exam held. In Figure, simultaneous substrates have been taken. After passing Minor 1 test you could give Minor 2 test. T

Database part of ldb?, Is it mandatory to declare all the tables in Report ...

Is it mandatory to declare all the tables in Report by the key word tables for all the tables that exist in the structure of LDB, and are being explained in the Database part of LD

Describe the development process of object oriented methods, Describe the d...

Describe the development process of Object oriented methods Object oriented methods have roots which are strongly anchored back in the 60s, functional and structured methods we

Database model, Why older data models are being replaced by new data modell...

Why older data models are being replaced by new data modelling 100 words accepted#

Keys, it can be possible to create any table without primary key

it can be possible to create any table without primary key

Explain the ansi sparc architecture, Explain the ANSI SPARC architecture ...

Explain the ANSI SPARC architecture The three-schema architecture is as well known as ANSI SPARC architecture. The aim of the three-schema architecture is to separate the user

Query to delete constraint from alter table, A constraint named less_than_2...

A constraint named less_than_20 was defined on the field date_of_birth of table student. Delete this constraint. ALTER TABLE student DROP CONSTRAINT less_than_20;

In the architecture of a database system which external leve, In the archit...

In the architecture of a database system which external level used? In the architecture of a database system view external level used.

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