Define multivalued dependency and 4nf, Database Management System

Assignment Help:

Define multivalued dependency and 4NF.

 Ans:  Multivalued Dependency - Assume R be a relation schema and let α ⊆ R and β ⊆ R. The multivalued dependency 

α →→β 

 holds on R if, in any type of legal relation r(R), for all pairs of tuples t1 and t2 in r like that 

t1[α] = t2[α], there exist tuples t3 and t4 in r like

t1[α] = t2[α] = t3[α] = t4[α]

t3[β] = t1[β]

t3[R - β] = t2[R - β]

t4[β] = t2[β]

t4[R - β] = t1[R - β]

 Fourth Normal Form (4 NF) - A relation schema R is in 4NF regarding to a set D of functional and multivalued dependencies if, for all multivalued dependencies in D+ of the

form α →→β, in which α ⊆ R and β ⊆ R, at least one of the subsequent holds:

  • α→→β is a trivial multivalued dependency,
  • α is a superkey for schema R.

Related Discussions:- Define multivalued dependency and 4nf

Mis, explain various steps uses in evaluation and maintenance of MIS.

explain various steps uses in evaluation and maintenance of MIS.

What is the function of io/m signal in the 8085, What is the function of IO...

What is the function of IO/M signal in the 8085? It is a status signal. It is used to differentiate among memory locations and I/O operations. When this signal is low (IO/M = 0

What is the need for triggers, What is the need for triggers? Triggers ...

What is the need for triggers? Triggers are useful mechanisms for alerting humans or for starting particular tasks automatically when particular conditions are met.

Find out the names of all employees from database, Find out the names of al...

Find out the names of all employees who work for first Bank Corporation from database. SELECT EMPLOYEE_NAME FROM WORKS WHERE COMPANYNAME = ‘First Bank Corporation';

How is the database organised in oracle, How is the database organised in O...

How is the database organised in Oracle? Database organized within Oracle in terms of table and table holds attributes and values. A database consists of one or more logical

Illustrate the view of software architecture, Illustrate the view of softwa...

Illustrate the view of software architecture A model is a semantically closed abstraction of system composes of elements. It can be visualized using any of the following five v

Explain the acid properties of a transaction, Explain the ACID properties o...

Explain the ACID properties of a transaction Ans: ACID properties are a significant concept for databases. The ACID stands for Atomicity, Consistency, Isolation, and Durability

State the step- implement software control designer, Implementing software ...

Implementing software control To implement software control designer must redesign strategy of state event model which is present in dynamic model. There are three basic ap

Define transitive dependencies, What do you understand by transitive depend...

What do you understand by transitive dependencies? Define with an example any two problems that can take place in the database if transitive dependencies are available in the datab

Examine about the behavioural diagrams, Examine about the Behavioural Diagr...

Examine about the Behavioural Diagrams  The main objective of behavioural diagrams is to visualize, specify, construct and document dynamic aspects of a system. The interactio

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