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

Concurrency control, discuss the purpose of the concurrency control?

discuss the purpose of the concurrency control?

OLD HOME POLICIES, Write an sql statement to find what is the percentage of...

Write an sql statement to find what is the percentage of home policies which are from the state of Arizona out of all Home policies by Policy Value.

Define the terms - physical schema and logical schema, Define the terms  1)...

Define the terms  1) physical schema 2) logical schema.  Physical schema:  The physical schema explains the database design at the physical level, which  is  the  lowest  lev

User error-database errors, User error :  This contains errors in the progr...

User error :  This contains errors in the program (e.g., Logical errors) with errors made by online users of database.  These types of errors can be avoided by applying some check

Explain the integrity constraints, Explain the integrity constraints: Not N...

Explain the integrity constraints: Not Null,  Unique, Primary Key with an example each. Is the combination 'Not Null, Primary Key' a valid combination. Justify. Not Null - Shou

OLAP CUBES, 1) Define a job scheduling strategy that will meet business req...

1) 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 pict

Differance between internal and external schema, Differance between interna...

Differance between internal and external schema? Internal and external schema: Internal Schema • Describes the physical storage structure • Uses a physical data model External

What is meant by heuristic optimisation, What is meant by heuristic optimis...

What is meant by heuristic optimisation?Discuss the major heuristics that are applied during query optimisation.

Payment processors, We have a buildup of payments that need to be processed...

We have a buildup of payments that need to be processed. You will need:- To prepare customer account on our site Process payment (you must have working Paypal account to d

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