Describes the several relationship constraints, Database Management System

Assignment Help:

Describes the several relationship constraints through giving suitable example?

Constraints on relationships: There are two kinds of constraints on relationships.

1) Mapping cardinalities or cardinality ratios express the number of entities to that another entity can be associated through a relationship set. For a binary relationship set among entities A and B. The mapping cardinality may be any one of the subsequent:

a) One to One: An entity in A is related along with at most one entity in B and an entity in B is related with at most one entity in A.
b) One to Many: An entity in A can be related with any number in B but an entity in B is associated with at most one in A.
c) Many to one: An entity in A is related with at most one in B but an entity in B is associated with any number in A.
d) Many to Many: An entity in A and B can be associated along with any number of entities in the other entity set.

2) Participation constraints: The participation of an entity set E in a relationship set R is said to be total if every entity in E participates within at least one relationship in R. If only a few entities in E participation of entity set E in relationship R is said to be partial.


Related Discussions:- Describes the several relationship constraints

What is relational model feature, What is relational model feature? A r...

What is relational model feature? A relational model feature is much more data independence than some other database models.

Explain about database system structure, Explain about database system stru...

Explain about database system structure? Storage manager Authorization and integrity manager Transaction manager File manager Buffer manager Storage manager

Write short notes on relational model, Write short notes on relational mode...

Write short notes on relational model The relational model uses a collection of tables to show both data and the relationships between those data. The relational model is an ex

What are partial and natural key, What are partial, alternate,, artificial,...

What are partial, alternate,, artificial, compound and natural key? Partial Key: It is a set of attributes that can uniquely recognize weak entities and that are related to s

Database design in third normal form, The following data are required to be...

The following data are required to be stored by a family physician. Family#, FamilyAddress, Patient#, PatientName, ServiceCode, ServiceFee, ServiceDate A family can have seve

How can you terminate the mysql server, How can you terminate the MySQL Ser...

How can you terminate the MySQL Server? Typing the following in Command prompt will shut down the server completely as root user % mysqladmin -u root -p shutdown

What is serialization and where it is used, What is serialization? Where it...

What is serialization? Where it is used and why?  Serialization is a basic term used for mechanisms which enable objects and object structures to be converted into portable for

In e-r diagram how derived attribute are represented, In E-R Diagram how de...

In E-R Diagram how derived attribute are represented ? In E-R Diagram By Dashed ellipse derived attribute are represented.

Create database and define relationships between tables, Instructions: ...

Instructions: Follow the instructions below for completing this project: 1. Creating the Database: · Use the physical table descriptions given below to define and create each t

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