dr gordon russell, copyright @ napier university m/c walkthrough - v2.0 1 multi-choice walkthrough

Dr Gordon Russell, CopyrigDr Gordon Russell, Copyright @ Napier Universityht @ Napier University

M/C Walkthrough - V2.0M/C Walkthrough - V2.0 11

Multi-Choice Multi-Choice WalkthroughWalkthrough



Q1Q1

A publishing company produces academic books on A publishing company produces academic books on various subjects. Books are written by authors who various subjects. Books are written by authors who specialise in one or more particular subject. The specialise in one or more particular subject. The company employs a number of editors who do not company employs a number of editors who do not have particular specialisations but who take sole have particular specialisations but who take sole responsibilty for for editing one or more publications. responsibilty for for editing one or more publications. A publication covers a single subject area but may be A publication covers a single subject area but may be written by one or more author - the contribution of written by one or more author - the contribution of each author is recorded as a percentage for the each author is recorded as a percentage for the purposes of calculating royalties.purposes of calculating royalties.



Q1 ContinuedQ1 Continued

The following ER diagram is intended to represent the The following ER diagram is intended to represent the above specification: above specification:

author subject

contribution

publication editor

specialises in

makes

to

is about

edits



Q1 OptionsQ1 Options

Indicate the relation which has an incorrect cardinality Indicate the relation which has an incorrect cardinality shown: shown:

A.A. specialises in specialises in

B.B. makes makes

C.C. is about is about

D.D. to to

E.E. None of the above None of the above



Q2Q2

The specification is to be changed so that an author The specification is to be changed so that an author can develop a publication covering more than one can develop a publication covering more than one subject area and that the schema must be able to subject area and that the schema must be able to store the percentage of the compents concerned with store the percentage of the compents concerned with each of the subjects. Select an appropriate change to each of the subjects. Select an appropriate change to the ER diagram: the ER diagram:

A.A. publication-subject becomes many to many publication-subject becomes many to many

B.B. author-subject becomes many to many author-subject becomes many to many

C.C. author-publication becomes many to many author-publication becomes many to many

D.D. more than one of the above more than one of the above

E.E. none of the above none of the above



Q3Q3

Consider the relational schema R(Consider the relational schema R(A,BA,B,C,D,E) with ,C,D,E) with non-key functional dependencies C,D - E and B - C. non-key functional dependencies C,D - E and B - C.

Select the strongest statement that can be made Select the strongest statement that can be made about the schema R about the schema R

A.A. R is in first normal form R is in first normal form

B.B. R is in second normal form R is in second normal form

C.C. R is in third normal form R is in third normal form

D.D. R is in BCNF normal form R is in BCNF normal form

E.E. None of the above None of the above



Q4Q4

Locking was introduced into databases so that Locking was introduced into databases so that

A.A. Keys can be provided to maintain security. Keys can be provided to maintain security.

B.B. Reading and writing is possible. Reading and writing is possible.

C.C. All simultaneous transactions are prevented. All simultaneous transactions are prevented.

D.D. Passwords can be provided to maintain security Passwords can be provided to maintain security

E.E. Consistency can be enforced. Consistency can be enforced.



Q5Q5

When accessing a disk block, the seek time When accessing a disk block, the seek time

A.A. is insignificant in comparison to transfer times is insignificant in comparison to transfer times

B.B. is about the same as transfer times is about the same as transfer times

C.C. greatly exceeds transfer times greatly exceeds transfer times

D.D. is the time taken to search for data in a sorted is the time taken to search for data in a sorted list of list of database rows database rows

E.E. is measured in nanoseconds is measured in nanoseconds



Q6Q6

Hash-table insertions Hash-table insertions

A.A. avoid hash-collisions by manipulating the avoid hash-collisions by manipulating the foreign keys foreign keys

B.B. might use hash-chains to allow hash-collisions might use hash-chains to allow hash-collisions

C.C. use balanced binary trees to allow hash-use balanced binary trees to allow hash-collisions collisions

D.D. use primary keys to avoid hash-collisions use primary keys to avoid hash-collisions

E. become unusable if there are any hash-collisions E. become unusable if there are any hash-collisions



Q7Q7

When a transaction aborts When a transaction aborts

A.A. all users must be notified all users must be notified

B.B. all changes it has made are immediately all changes it has made are immediately available to otheravailable to other transactions transactions

C.C. the modifications of all transactions currently the modifications of all transactions currently running arerunning are also aborted also aborted

D.D. it can abort transactions which have already it can abort transactions which have already committed committed

E. it releases all of its locks E. it releases all of its locks

dr gordon russell, copyright @ napier university m/c walkthrough - v2.0 1 multi-choice walkthrough

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