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

Define the division operation of relational algebra, Define the Division Op...

Define the Division Operation of Relational Algebra Let R be a relation comprising attributes (A1,...Ap,Ap+1,...An) and S comprising attributes (Ap+1,...An)  DEF: Division

Explain the weak entity set, Explain the Weak Entity Set An Entity set...

Explain the Weak Entity Set An Entity set which does not have sufficient attribute to make a primay key is known as weak entity set. For instance, dependents of an employee in

Explain deadlock detection and recovery, Explain Deadlock detection and rec...

Explain Deadlock detection and recovery Deadlock Detection - A deadlock is said to take place when there is a circular chain of transaction, every waiting for the release of a

Replication-design of distributed databases, Replication : It is definite a...

Replication : It is definite as a copy of a relation. Every replica is stored at a dissimilar site. The alternative to replication is to store only single copy of a relation which

Cascading, what is cascading? what is rollback cascading? please explain in...

what is cascading? what is rollback cascading? please explain in detail

Subclassing, In the ER diagram, one example of subclassing is depicted foll...

In the ER diagram, one example of subclassing is depicted following the Services entity. The subclasses Item Based and Time Based are created. The entity Services gains the attribu

Why dml is used for, Why DML is used for? DML is used to Manipulation and...

Why DML is used for? DML is used to Manipulation and processing of database. DML is provided for manipulation & processing of database. (Data stored in the database is processed

Discuss along with examples about several types of er model, Discuss along ...

Discuss along with examples about several types of attributes present in the ER model? Types of Attributes are: • SIMPLE attributes are attributes which are drawn from the ato

What is system r?what are its two major subsystems?, System R was develop...

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

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