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

Create role named roletable to allows a user to create table, Create role n...

Create role named role_table that allows a user to create tables. Using role_table allow users kripa and reena to create tables. CREATE ROLE role_table; GRANT CREATE ANY TABLE

What is recursive closure and operation relational algebra, What is recursi...

What is recursive closure? Why is it not possible to describe this operation in relational algebra? Recursive closure is applied to recursive relationship. An instance of rec

Explain what is aggregation, Explain what is Aggregation ? Aggregation...

Explain what is Aggregation ? Aggregation: This is used whenever we intend to show a relationship between an entity and the relationship. There is no provision for this in th

Describe in brief about object oriented design, Describe about Object orien...

Describe about Object oriented design Object oriented design is concerned with developing an object oriented model of a software system to implement known requirements. Many OO

What is datawarehousing, What is DataWarehousing? Subject-oriented, me...

What is DataWarehousing? Subject-oriented, meaning that the data in the database is organized so that all the data elements relating to the similar real-world event or object

Log, what is the need of a log in dbms

what is the need of a log in dbms

Differences between a file processing system and a dbms, List any two signi...

List any two significant differences between a file processing system and a DBMS. File Processing System vs. DBMS Data Independence - Data independence is the capacity t

When are they useful justify with an example, When are they useful? Justify...

When are they useful? Justify with an example. The temporary tables are commonly used to support specialized rollups or exact application processing needs. Unlike a permanent t

Give the relational calculus queries of players in sql, An orchestra databa...

An orchestra database consists of the following relations: CONDUCTS (conductor, composition) REQUIRES (composition, Instrument) PLAYS (Player, Instrument) Give the relational

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