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 the concept of design documentation, Design Documentation  The ...

Design Documentation  The Design Document shall be an extension of Requirements Analysis Design. "The Design Document will comprise a revised and much more detailed descrip

What are stand-alone procedures, What are stand-alone procedures? Proce...

What are stand-alone procedures? Procedures that are not part of a package are called as stand-alone because they independently defined. A good example of a stand-alone procedu

Define granularity and hierarchy of granularity of locks, Define granularit...

Define granularity, hierarchy of granularity of locks & multiple granularity locking. Explain the modified two phase locking along with multiple granularity locking. Ans: The s

What is conceptual schema, What is conceptual schema? The schemas at th...

What is conceptual schema? The schemas at the view level are known as subschema that describe dissimilar views of the database.

Create role named roletable to allows a user to create table, Create role n...

Create role named role_table that allows a user to create tables. Using role_table allow users kripa and reena to create tables. CREATE ROLE role_table; GRANT CREATE ANY TABLE

The need for three level architecture, The need for three level architectur...

The need for three level architecture The aim of the three level architecture is to divide each user's view of the database from the way the database is physically shown.

Illustrate the diagram - association as a cache, Association as a cache ...

Association as a cache This association must be updated when any new element is added to it, but testing for overlap using association is more efficient.    Figure:

Weak entity, Entity types that do not have any key attribute, and therefore...

Entity types that do not have any key attribute, and therefore cannot be identified independently, are known as weak entity types. A weak entity can be recognized uniquely only by

Wound-wait scheme-deadlock prevention, " Wound-wait" scheme : It is based o...

" Wound-wait" scheme : It is based on a preemptive method. It is based on a simple rule:                   If Ti requests a database resource that is held by Tj

Heuristics, Benefits of using heuristics

Benefits of using heuristics

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