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

What is an object design, What is an object design? Object design is a ...

What is an object design? Object design is a very interactive method, which decides the relationship among objects, classifies operations on classes, determines overall system

What is online transaction processing, What is OLTP (Online Transaction Pro...

What is OLTP (Online Transaction Processing)? In OLTP - online transaction processing systems relational database design use the discipline of data modeling and generally follo

What is substitutability, What is substitutability? Any method of a cla...

What is substitutability? Any method of a class-say A can equally well be adjured with any object belonging to any subclasses B of A. This characteristic leads to code reuse, a

Create a database of a motor bike racing club, You have a friend that runs ...

You have a friend that runs a motor bike club that holds racing events at various venues on weekends, on a monthly basis. Some venues are private race tracks and some are dirt trac

Explain the disadvantages of using dbms, Explain the disadvantages of using...

Explain the disadvantages of using DBMS There could be a few disadvantages of using DBMS. As DBMS requires computers, we have to invest a good amount in acquiring the hardwa

Describes the several relationship constraints, Describes the several relat...

Describes the several relationship constraints through giving suitable example? Constraints on relationships: There are two kinds of constraints on relationships. 1) Mapping

Multivalued attributes, For every multivalued attribute 'A', we make a new ...

For every multivalued attribute 'A', we make a new relation R that contains an attribute corresponding to plus the primary key attribute k of the relation that shows the entity typ

Give example of relational schema, An instance of relational schema R (A, B...

An instance of relational schema R (A, B, C) has distinct values of A including NULL values. then A is a candidate key or not? If relational schema R (A, B, C) has distinct val

Main difference between read-only and update methods, What is the main diff...

What is the main difference between read-only and update methods? A read-only method does not affect the values of a variable in an object, whereas an update method may alter t

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