What value represents missing, unknown, or inapplicable data in a relational database? MCQ with Answer and Explanation

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What value represents missing, unknown, or inapplicable data in a relational database?

A. Blank Space (' ')

B. NULL

C. Zero (0)

D. Void

Answer: Option B

Solution (By JKSSB Mock Tests)

NULL is a special marker used in SQL to indicate the absence of a value or that the data is missing, unknown, or not applicable.

This question belongs to: Computer Database Management System (DBMS)

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Question #1

What is the main advantage of using a DBMS over a file system?

A. Data security and access control are provided

B. Data redundancy is minimized

C. Data consistency is maintained

D. All of the above

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Correct Answer: Option D

Explanation:
A DBMS offers advantages like reduced redundancy, consistency, security, concurrent access, and backup/recovery compared to file systems.

This question belongs to: Computer Database Management System (DBMS)

Question #2

What is the situation called when two or more transactions are permanently blocked, each waiting for a lock held by the other transaction to be released?

A. Concurrency

B. Isolation failure

C. Deadlock

D. Starvation

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Correct Answer: Option C

Explanation:
A Deadlock occurs when two or more transactions are stuck in a circular dependency, each waiting for resources locked by the other, preventing progress.

This question belongs to: Computer Database Management System (DBMS)

Question #3

What is the purpose of the SQL 'ORDER BY' clause?

A. To group rows

B. To filter rows

C. To sort the result set

D. To join tables

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Correct Answer: Option C

Explanation:
ORDER BY sorts the query results in ascending or descending order based on specified columns.

This question belongs to: Computer Database Management System (DBMS)

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