Extended e-r features, Database Management System

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

Posted Date: 3/6/2013 6:14:49 AM | Location : United States







Related Discussions:- Extended e-r features, Assignment Help, Ask Question on Extended e-r features, Get Answer, Expert's Help, Extended e-r features Discussions

Write discussion on Extended e-r features
Your posts are moderated
Related Questions
List the set operations of SQL? 1) Union 2) Intersect operation 3) The except operation

An employee record has the following structure struct employee { int eno; char name[22]; float salary; char dept[10];}; (i) Calculate the record size R in bytes.

System R was developed and designed over a period of 1974-79 at IBM San Jose Research Company. Its purpose was to illustrate that it is possible to create a Relational System tha

Operator Precedence The basic operators used in SQL are * /   - + Operators of the similar priority are evaluated From Left to right Parentheses are used to force priorit

What is a checkpoint? List the operations to be performed by the system when a checkpoint is to be taken. What does the recovery system do if there is a crash? There is large n

The natural join is equal to which product? The natural join is equal to Combination of projection and Cartesian product

Improved Reliability: In a centralised DBMS, a server failure stops the operations of the DBMS. Though, a failure at single site of a DDBMS, or a failure of a communication link cr

Question A What is operational intelligence? Question B What is Business Intelligence? Explain the components of BI architecture Question C Differentiate between databas

We face problem of stock Opening balance and closing balance in Minus

Explain the conventions for displaying an ER schema as an ER diagram? An E-R Diagram scheme might describe certain constraints to that the contents of a database must conform.