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

The second normal form (2nf), The Second Normal Form (2NF) Definition: ...

The Second Normal Form (2NF) Definition: A relation is in 2NF if it is in 1NF and each non-key attribute is fully dependent on each candidate key of the relation. Some of th

What are the properties in a relation, What are the properties in a relatio...

What are the properties in a relation ? In a relation Ordering of rows is immaterial and No two rows are identical.

Express the properties of strings, Express the properties of Strings? ...

Express the properties of Strings? Strings can be case sensitive (or not) which can change the outcome of string operations. You can evaluate whole strings \ just part

Relationships, Let us first describe the term relationships. What Are Re...

Let us first describe the term relationships. What Are Relationships? A relationship can be defined as: A set of associations or connection, or A rule for communic

Write a query to find name from the relational algebra, Consider the relati...

Consider the relations City (city_name, state) Hotel (name, address) City_hotel (hotel_name, city_name, owner) Answer the following queries in relational algebra (i) Find

What is an index, What is an Index? An index is a small table having on...

What is an Index? An index is a small table having only two columns. The first column has a copy of the primary or candidate key of a table and the second column having a set o

Define catalog and meta data, Define Catalog and meta data ? A catalog ...

Define Catalog and meta data ? A catalog is a compilation of records elaborating the contents of a particular collection or group of collections. Metadata (Meta data, or someti

Describe the concept of aggregation, Aggregation Aggregation is strong...

Aggregation Aggregation is stronger form of association. It represents the "has-a" or "part-of" relationship. An aggregation association depicts a complex object which is comp

Dealing with constraints violation, If the deletion violates referential in...

If the deletion violates referential integrity constraint, then three alternatives are available: Default option: - refuse the deletion. It is the job of the DBMS to describ

Define the term- having clause and a where clause, What is the difference ...

What is the difference between a HAVING CLAUSE and a WHERE CLAUSE? HAVING CLAUSE - HAVING CLAUSE is used only with SELECT statement. - It is normally used in a GROUP BY

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