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MCQ | SQL – SET Operators

SQL SET Operators MCQ: This section contains the Multiple-Choice Questions & Answers on SQL SET Operators.
Submitted by Anushree Goswami, on October 18, 2021

1. SET Operators are used to –

  1. Compile the results from two queries
  2. Compile the results from three queries
  3. Compile the results from four queries
  4. 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.


2. Name of the operators in SET Operators is –

  1. UNION
  2. INTERSECT
  3. MINUS
  4. All of the above

Answer: D) All of the above

Explanation:

Name of the operators in SET Operators is –

  1. UNION
  2. INTERSECT
  3. MINUS

3. Rules that are needed to be followed in SET Operators in SQL are –

  1. All columns must be identical in number and order.
  2. There must be compatibility between data types.
  3. Both A and B
  4. None of the above

Answer: C) Both A and B

Explanation:

Rules that are needed to be followed in SET Operators in SQL are –

  1. All columns must be identical in number and order.
  2. There must be compatibility between data types.

4. Combining the results of ___ select statements will be done using UNION.

  1. One
  2. Two
  3. Three
  4. Four

Answer: B) Two

Explanation:

Combining the results of two select statements will be done using UNION.


5. What is TRUE about UNION ALL Operator?

  1. The results of both queries are combined with this operator.
  2. After performing the UNION ALL operation, duplicate rows will not be removed.
  3. Both A and B
  4. None of the above

Answer: C) Both A and B

Explanation:

In the case of UNION ALL Operator –

  1. The results of both queries are combined with this operator.
  2. After performing the UNION ALL operation, duplicate rows will not be removed.

6. A SELECT statement is intersected to use it as a join, but it only returns the records that are ________ between both statements.

  1. Distinct
  2. Common
  3. Shared
  4. 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.


7. MINUS Operator displays the rows which are –

  1. Detected in the second query, absent in the first query, and there are no duplications.
  2. Detected in the first query, absent in the second query, and there are no duplications.
  3. Detected in the first query, absent in the second query, and there are duplications.
  4. 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.


8. What is the difference between UNION & UNION ALL operators?

  1. Combining the results of two select statements will be done using UNION whereas combined records from both queries are returned by UNION ALL operator.
  2. Combining the results of two select statements will be done using UNION ALL whereas combined records from both queries are returned by UNION operator.
  3. After performing the UNION operation, duplicate rows will not be removed whereas after performing the UNION ALL operation, duplicate rows will be removed.
  4. 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 –

  1. Combining the results of two select statements will be done using UNION whereas combined records from both queries are returned by UNION ALL operator.
  2. 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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