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

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 deadlock prevention, Define deadlock prevention. Deadlock preven...

Define deadlock prevention. Deadlock prevention is a set of methods for ensuring that at least one of the four essential conditions like mutual exclusion, hold and wait, no pre

Explain the management of data store, Explain the Management of Data Store ...

Explain the Management of Data Store Every system irrespective of its nature of application requires storing permanent data for consequent use in problem solving. Some objects

Built online transaction processing, Question: A DBMS built for Online ...

Question: A DBMS built for Online Transaction Processing (OLTP) is generally regarded as unsuitable for data warehousing. Each system is designed with a different set of requir

Describe the different raid levels, Describe the different RAID levels.  Di...

Describe the different RAID levels.  Discuss the choices of the different RAID levels for different applications.          Ans:   There are several combinations of these approa

The structured query language, The Structured Query Language INTRODUCT...

The Structured Query Language INTRODUCTION Database is an organised set of information about an entity having controlled redundancy and serves numerous applications. DBMS

What is known as clustering file organization, What is known as clustering ...

What is known as clustering file organization? In the clustering file organization, records of several dissimilar relations are stored in the similar file.

Explain disadvantages of a dbms, Question : (a) Database Management Sy...

Question : (a) Database Management Systems (DBMS) is the foundation of business intelligence. Explain the following concepts related to DBMS: (i) Entity Relationship Diagr

Define access time, Define access time. Access time is the time from wh...

Define access time. Access time is the time from when a read or write request is issued to when data transfer starts.

Indexed (indexed sequential) file organisation, Indexed (Indexed Sequential...

Indexed (Indexed Sequential) File Organisation It organises the file like a big dictionary, i.e., records are kept in order of the key but an index is stored which also allows

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