Relation instance or relation state, Database Management System

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'.

Posted Date: 3/6/2013 5:17:29 AM | Location : United States







Related Discussions:- Relation instance or relation state, Assignment Help, Ask Question on Relation instance or relation state, Get Answer, Expert's Help, Relation instance or relation state Discussions

Write discussion on Relation instance or relation state
Your posts are moderated
Related Questions
Explain data dictonary on oracle ? Data Dictionary - Data dictionaries are the system tables in which contain descriptions of the database objects and how they are structured.

The indices are accumulated in the index files. The data is accumulated in the data files. Indices give fast access to data items. For example, a book database may be managed in th

Replicating Data One approach that may support efficient access to dissimilar applications as above may be to give access to every of the applications from dissimilar replicate

Explain how the associations are implemented as classes. A general approach in this case is to transform an association class into a simple class linked to two original classes

why shadow copy technique is used?

Explain the ISA relationship Answer: ISA relationship - ISA notation is employed in generalization/ specialization to depict relationship among lower and higer level entity s

Failure Controlling Methods: Failures can be handled using different recovery methods that are talk about later in the unit. But the first question is doing we really require recov

What type of view of total database content? Data base content Conceptual view of total database contain.

What is relationship? Give examples A relationship is an association between several entities. Example: A depositor relationship associates a customer with every account tha

Describe Embedded Query Language? Embedded Query Language - A query language (e.g., SQL) can be implemented in two ways. It can be used interactively or embedded within a host