Which SQL set operator combines the output of two queries but preserves all duplicate rows without filtering them? MCQ with Answer and Explanation

Question

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Which SQL set operator combines the output of two queries but preserves all duplicate rows without filtering them?

A. UNION

B. UNION ALL

C. MINUS

D. INTERSECT

Answer: Option B

Solution (By JKSSB Mock Tests)

UNION ALL appends the results of multiple SELECT queries together without performing any deduplication, making it faster than UNION.

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

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Question #1

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Which clause is used in SQL to sort the final query result set in ascending or descending order?

A. ORDER BY

B. ARRANGE BY

C. SORT BY

D. GROUP BY

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Correct Answer: Option A

Explanation:
The ORDER BY clause is used to sort the result set of a query in either ascending (default) or descending (using DESC) order.

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

Question #2

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In SQL, which operator is used to combine two conditions and returns true if both are true?

A. NOT

B. XOR

C. AND

D. OR

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Correct Answer: Option C

Explanation:
The AND operator returns true only if both conditions are true.

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

Question #3

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What is the purpose of a Foreign Key?

A. To create indexes

B. To sort data

C. To link two tables and enforce referential integrity

D. To uniquely identify records

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Correct Answer: Option C

Explanation:
A foreign key establishes a relationship between tables and maintains referential integrity.

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

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