A ________ is a reference to a field in another relation or table
(a) Primary key
(b) Candidate key
(c) Foreign key
(d) Super key
1 Answers
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What is super conductivity?
1. The resistivity of a metal decreases as the temperature decreases. 2. In case of some metals and metal alloys, the resistivity suddenly drops to zero at a particular temperature (Tc), this...
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What do you understand by terms ‘primary key’ and ‘secondary key’ in a database?
A primary key is a field that identifies each record in a database table admitting that the primary key must contain its UNIQUE values. A secondary key shows the secondary value...
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The correct order of sentences related to preparation of super saturated solution is P. Add one more spoon of sugar to it
A) Q, S, P, R
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If A={a,b,c,d}, then on A . (i) write the identity relation `I_(A)` . (ii) write a reflexive relation which is not the identity relation.
Correct Answer - (i) {(a,a),(b,b),(c,c),(d,d)} `" "` {(a,a),(b,b),(c,c),(d,d),(a,c),(b,d)}
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What is the key difference between primary and secondary sewage treatment?
Primary treatment involves the removal of large sized floating and suspended solids by physical methods, while secondary treatment involves decomposition of organic matter by microbial action.
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Pick the key which can not be used to uniquely identify a tuple on a relation:
None of these.
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1. Choose the odd one from the following. Primary key, Unique, Distinct, Default, Check
1. Distinct 2. Distinct is used with select command while others are column constraints of create table command.
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Assertion: Hoffmann’s bromamide reaction is given by primary amines. Reason: Primary amines are more basic than secondary amines.
(iii) Assertion is correct statement but reason is wrong statement.
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Why is glass considered a super cooled liquid?
Glass is an amorphous solid. These amorphous solids do not have regular arrangement of constituent particles for a longer distance, unlike the crystalline solids. The structure of the amorphous solids...
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Define primary key with an example.
A field which uniquely identifies each record in a table is known as the primary key. e.g. emp id is the primary key of the Employee table.
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