Database-Oracle [3i Infotech Placement]: Sample Questions 21 - 22 of 132

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Question 21

Oracle

Question

MCQ▾

Which of the following is not an advantage of a client/server model?

Choices

Choice (4)

a.

A client/server model allows centralised control of data and centralised implementation of business rules.

b.

A client/server model is suitable for all applications

c.

A client/server model increases developer՚s productivity

d.

All of the above

Answer

b.

Explanation

Client/Server Model

Advantages of Client-Server Model

Centralization

  • Updating data or other resources at central location.
  • Integrity of the data controlled by the dedicated server.

Proper Management

  • The files are stored at the same place- management of files becomes easy.

Suitable for All Application

  • A client-server application is a distributed system made up of both client and server software.
  • Client server application provides a better way to share the workload.

Multitasking

  • Delivers the highest possible degree of concurrency, data integrity, and performance to its client applications.

Question 22

Oracle

Question

MCQ▾

Spurious tuples may occur due to

  1. Bad normalization
  2. Theta joins
  3. Updating tables from join

Which is correct?

Choices

Choice (4)

a.

1 and 2

b.

1 and 3

c.

1,2 and 3

d.

2 and 3

Answer

b.

Explanation

  • Spurious tuples may occur due to bad normalization and theta join.
  • Bad normalization design for a relational database may result in erroneous result for join operation.
  • A record in a database that gets created when two tables are joined badly.
  • Spurious tuples are created when two tables are joined on attributes that are neither primary keys nor foreign keys.
  • Lead to an integrity issue since only primary keys are unique.
  • To prevent spurious tuples, avoid joining relations consisting of matching attributes that are not combinations as joining on such attributes.

Theta Joins

  • Theta joins are joins made on keys that are not primary keys.
  • Combine tuples from different relations provided they satisfy the theta condition.
  • Condition is denoted by the symbol .

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