Relation instance or relation state, Database Management System

Assignment Help:

A relation instance indicates as r is a collection of tuples for a given relational schema at a exact point of time.

A relation state r of the relation schema R (A1,A2,..........AN), also denoted by r(R) is a set of n-tuples

r = {t1,t2,............tm}

Where each n-tuple is an ordered list of n values

t  =  1,v2,........, vn>

where every vi belongs to domain (Ai) or includes null values.

The relation schema is also known as  'intension' and relation state is also known as 'Extension'.


Related Discussions:- Relation instance or relation state

Define thomas write rule, Define Thomas write rule Thomas' write rule: ...

Define Thomas write rule Thomas' write rule: The Thomas' write rule is a modification of timestamp-ordering protocol for concurrency control. Assume that transaction T i issue

Define garbage collection, Define garbage collection. Garbage may be fo...

Define garbage collection. Garbage may be formed also as a side effect of crashes. Periodically, it is essential to find all the garbage pages and to add them to the list of fr

Update city of first bank corporation to new delhi, Change the city of Firs...

Change the city of First Bank Corporation to ‘New Delhi' UPDATE COMPANY SET CITY = ‘New Delhi' WHERE COMPANY_NAME = ‘First Bank Corporation';

Although how will the system recover, Although how will the system recover ...

Although how will the system recover The selection of REDO or UNDO for a transaction for the recovery is completed on the basis of the state of the transactions. This state is

Define value set, Define value set? Value set: It is a set of values. Y...

Define value set? Value set: It is a set of values. You do not always need a user to enter junk free text within all the fields. Therefore, Oracle Apps uses value set to valida

Which method is used to key transformation, Which method is used to key tra...

Which method is used to key transformation ? A hash method is used to key transformation.

What is a recursive relationship, Question: (a) Can a set of data requi...

Question: (a) Can a set of data requirements be correctly modelled by two or more different ER diagrams? Explain your answer. You may use a small example, if you think it will

What is hierarchical dbms, What is Hierarchical DBMS In HDBMS, data is ...

What is Hierarchical DBMS In HDBMS, data is structured in a tree like manner. There is a parent-child relationship between data items and the data model is very suitable for re

What is odbc, What is ODBC ? ODBC - Open DataBase Connectivity which i...

What is ODBC ? ODBC - Open DataBase Connectivity which is also denoted by ODBC enable the integration of SQL along with a common-purpose programming language. ODBC expose data

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