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SQL SET Operators MCQ: This section contains the Multiple-Choice Questions & Answers on SQL SET Operators.
Submitted by Anushree Goswami, on October 18, 2021
SQL SET Operators MCQs
1. SET Operators are used to –
- Compile the results from two queries
- Compile the results from three queries
- Compile the results from four queries
- Compile the results from five queries
Answer: A) Compile the results from two queries
Explanation:
SET Operators are used to compile the results from two queries.
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2. Name of the operators in SET Operators is –
- UNION
- INTERSECT
- MINUS
- All of the above
Answer: D) All of the above
Explanation:
Name of the operators in SET Operators is –
- UNION
- INTERSECT
- MINUS
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3. Rules that are needed to be followed in SET Operators in SQL are –
- All columns must be identical in number and order.
- There must be compatibility between data types.
- Both A and B
- None of the above
Answer: C) Both A and B
Explanation:
Rules that are needed to be followed in SET Operators in SQL are –
- All columns must be identical in number and order.
- There must be compatibility between data types.
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4. Combining the results of ___ select statements will be done using UNION.
- One
- Two
- Three
- Four
Answer: B) Two
Explanation:
Combining the results of two select statements will be done using UNION.
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5. What is TRUE about UNION ALL Operator?
- The results of both queries are combined with this operator.
- After performing the UNION ALL operation, duplicate rows will not be removed.
- Both A and B
- None of the above
Answer: C) Both A and B
Explanation:
In the case of UNION ALL Operator –
- The results of both queries are combined with this operator.
- After performing the UNION ALL operation, duplicate rows will not be removed.
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6. A SELECT statement is intersected to use it as a join, but it only returns the records that are ________ between both statements.
- Distinct
- Common
- Shared
- Both B and C
Answer: D) Both B and C
Explanation:
A SELECT statement is intersected to use as a join, but it only returns the records that are common or shared between both statements.
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7. MINUS Operator displays the rows which are –
- Detected in the second query, absent in the first query, and there are no duplications.
- Detected in the first query, absent in the second query, and there are no duplications.
- Detected in the first query, absent in the second query, and there are duplications.
- Detected in the second query, absent in the first query, and there are duplications.
Answer: B) Detected in the first query, absent in the second query, and there are no duplications
Explanation:
Detected in the first query, absent in the second query, and there are no duplications.
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8. What is the difference between UNION & UNION ALL operators?
- Combining the results of two select statements will be done using UNION whereas combined records from both queries are returned by UNION ALL operator.
- Combining the results of two select statements will be done using UNION ALL whereas combined records from both queries are returned by UNION operator.
- After performing the UNION operation, duplicate rows will not be removed whereas after performing the UNION ALL operation, duplicate rows will be removed.
- None of the above
Answer: A) Combining the results of two select statements will be done using UNION whereas combined records from both queries are returned by UNION ALL operator
Explanation:
Difference between UNION & UNION ALL operators is –
- Combining the results of two select statements will be done using UNION whereas combined records from both queries are returned by UNION ALL operator.
- After performing the UNION ALL operation, duplicate rows will not be removed whereas after performing the UNION operation, duplicate rows will be removed.
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