Database [3i Infotech Placement]: Sample Questions 43 - 44 of 294

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Question 43

Database

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 .

Question 44

Database
Edit

Describe in Detail

Essay▾

What is File Manager?

Explanation

Understanding of File Manager
  • Software program that helps a user manage all the files on their computer.
  • Ex. All file managers allow the user to view, edit, copy, and delete the files on their computer.
  • Some file managers contain features inspired by web browsers, including forward and back navigational buttons.
  • Can be implemented using an interface to the existing file subsystem provided by the operating system of the host computer or it can include a file subsystem written especially for the DBMS.

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