What is a candidate key in a relation? MCQ with Answer and Explanation

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What is a candidate key in a relation?

A. A foreign key

B. Any column that can be used as a primary key

C. A key that is not unique

D. A super key that is minimal

Answer: Option D

Solution (By JKSSB Mock Tests)

A candidate key is a minimal super key, meaning no subset of it can uniquely identify a row.

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

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Practice More Database Management System (DBMS) Questions

Question #1

What is a deadlock in a database?

A. A query error

B. A system crash

C. A type of backup

D. A situation where two or more transactions are waiting indefinitely for each other to release locks

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Correct Answer: Option D

Explanation:
Deadlock occurs when each transaction holds a lock that the other needs, resulting in a circular .

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

Question #2

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

A. Blank Space (' ')

B. NULL

C. Void

D. Zero (0)

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Correct Answer: Option B

Explanation:
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)

Question #3

Which of the following is NOT an advantage of DBMS over traditional file systems?

A. Simpler implementation and lower cost

B. Data independence

C. Data redundancy control

D. Higher data security

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Correct Answer: Option A

Explanation:
DBMS generally involves higher initial costs and complexity compared to simple file systems, though it offers better control over redundancy, independence, and security.

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

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