Which of the following operators is used in a correlated subquery?

  1. IN

  2. EXISTS

  3. UNION

  4. INTERSECT


Correct Option: B

AI Explanation

To answer this question, you need to understand the concept of correlated subqueries.

A correlated subquery is a subquery that refers to a column from a table in the outer query. The subquery is executed once for each row of the outer query, and the results of the subquery are correlated to the current row of the outer query.

Among the given options, the operator used in a correlated subquery is the EXISTS operator.

Option A) IN - The IN operator is used to compare a value to a list of values or a subquery. It is not specifically used in a correlated subquery.

Option B) EXISTS - The EXISTS operator is used to check if a subquery returns any rows. It is commonly used in a correlated subquery to check for the existence of specific rows in the outer query.

Option C) UNION - The UNION operator is used to combine the result sets of two or more SELECT statements. It is not specifically used in a correlated subquery.

Option D) INTERSECT - The INTERSECT operator is used to return the common rows between two SELECT statements. It is not specifically used in a correlated subquery.

The correct answer is option B) EXISTS. This operator is used in a correlated subquery to check for the existence of specific rows in the outer query.

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