Super keys, Database Management System

Assignment Help:

A super key is an attribute or set of attributes used to recognize the records uniquely in a relation.

For instance, in the Relation PERSON defines earlier PERSON_ID is a super key since PERSON_ID is unique for every person. Likewise (PERSON_ID, AGE) and (PERSON_ID, NAME) are also super keys of the relation PERSON as their combination is also unique for each record.


Related Discussions:- Super keys

Explain the disadvantages of a file processing system, Explain the disadvan...

Explain the disadvantages of a file processing system? Ans: Disadvantages of File Processing Systems include: 1) Data Redundancy 2) Data Inconsistency 3) Difficult to acce

What are the types of reference, What are the types of reference?explain it...

What are the types of reference?explain it with suitable examples? Object oriented language given the ability to refer the object attribute of the type can be referred to the s

Trigger , Flights(FlightNo, DeptDateTime, Origin, ArrivalDateTime, Destinat...

Flights(FlightNo, DeptDateTime, Origin, ArrivalDateTime, Destination, Capacity, SoldSeats) Tickets(FlightNo, Seat, CustID) Where - flightNo is the PK of the flights table - DeptDa

What is the purpose of storage manager, What is the purpose of storage mana...

What is the purpose of storage manager? The storage manager is responsible for the following a) Interaction with the file manager b) Translation of DML commands in to low

ERD, The entity type STUDENT has the following attributes: Student Name, Ad...

The entity type STUDENT has the following attributes: Student Name, Address, Phone, Age, Activity, and No of Years. Activity represents some campus-based student activity, and No o

Differance between join and outer join, Differentiate between join and oute...

Differentiate between join and outer join? Outer joins return all rows from at least one of the tables or views mentioned within the FROM clause, as long as those rows get toge

Compare the two log based recovery schemes, Compare the two log-based recov...

Compare the two log-based recovery schemes in terms of ease of implementation and overhead cost.    Ans:  There are two types of log based recovery techniques: deferred update

Relation instance or relation state, A relation instance indicates as r is ...

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 (A 1 ,A 2 ,.....

Using relational algebra which query finds customers, Using Relational Alge...

Using Relational Algebra which query finds customers, who have a balance of over 1000 ? Using Relational Algebra Π Customer_name( σ balance >1000(Deposit)) is query to find cu

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