Explain algorithm of er to relational mapping, Database Management System

Assignment Help:

Explain algorithm of ER To Relational Mapping ?

ER-to-Relational Mapping Algorithm:

1) Step 1: Mapping of regular entity types: For each strong entity type E, form a relation T which involves all the easy attributes of a composite attribute.

2) Step2: Mapping of weak entity types: For each weak entity type W along with owner entity type E, create relation R and involve all easy attributes (or simple components of composite attributes) of W as attributed of R. In addition, involves as foreign key attributes of R, the primary key attribute (s) of relation(s) which correspond to the owner(s) and the partial key of the weak entity type W, if any.

3) Mapping of relationship types: form a relation R, for relationship along with primary keys of participating relations A and B as foreign keys in R. Further to this, any attributes of relationship become an attribute of R also.

4) Mapping of multivalued attributes: For every multilvalued attribute A, form a new relation R. This relation R will involve an attribute corresponding to A, plus primary key attribute K-as a foreign key in R-of the relation which represents the entity category or relationship type that has A as an attribute.


Related Discussions:- Explain algorithm of er to relational mapping

Example of sequences, Example : Create a sequence named SEQSS that starts a...

Example : Create a sequence named SEQSS that starts at 105, has a step of 1 and can take maximum value as 2000.  CREATE SEQUENCE SEQSS START WITH 105 INCREMENT BY 1 MAX VA

Explain how the law ensures data protection and security, Question 1: (...

Question 1: (a) Explain the legal meaning of :- (i) Computer Service Person (ii) Data holding (b) Explain how the law ensures Data protection and Security. Qu

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

Datawarehouse, How to define a job scheduling strategy that will meet busin...

How to define a job scheduling strategy that will meet business requirement of reporting availability by 6am CST for the following cubes? Show the job scheduling dependencies in a

Explain cursors in sql, Explain cursors in SQL? Cursors in SQL - An o...

Explain cursors in SQL? Cursors in SQL - An object used to store the output of a query for row-through-row processing through the application programs. Cursors are constructs

What is data model, A Data Model in software engineering is an abstract...

A Data Model in software engineering is an abstract model that organizes and documents the business data for interaction between team members and is used as a plan for creating

Decomposition properteis, what is lossless & dependency preserving decompo...

what is lossless & dependency preserving decomposition ?

What are the disadvantages of relational approach, What are the disadvantag...

What are the disadvantages of relational approach? Disadvantages of relational approach: • Substantial hardware and system software overhead • May not fit all business models •

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