Which operators are used when a subquery returns multiple rows to be evaluated in comparison to the outer query?

Solution (By Examveda Team)

This question is about how to handle situations when a subquery (a query nested inside another query) produces multiple results. Think of it like this:
Imagine you have a list of students and their favorite colors.
The outer query might be "Find all students who like blue."
The subquery could be "Find all the colors students like."
Now, if the subquery returns multiple colors, how do you compare those to the outer query's condition ("like blue")?
Here's where the options come in:
Option A: IN and NOT IN
IN checks if a value is present in a set of values. NOT IN checks if a value is *not* present in a set of values.
Example: "Find all students whose favorite color is in the list of 'blue', 'green', and 'red'."
Example: "Find all students whose favorite color is not in the list of 'blue', 'green', and 'red'."
Option B: EXISTS and NOT EXISTS
EXISTS checks if a subquery returns any rows. NOT EXISTS checks if a subquery returns *no* rows.
Example: "Find all students where there exists a color in the subquery that is 'blue'."
Example: "Find all students where there does not exist a color in the subquery that is 'blue'."
Option C: OUTER JOIN and INNER JOIN
Joins are used to combine data from multiple tables. They're not directly used to compare subquery results with the outer query's condition.
Option D: LEFT JOIN and RIGHT JOIN
These are also types of joins, similar to Option C. They are not used for comparing subquery results.
The answer:
The correct answer is Option A: IN and NOT IN.
IN and NOT IN are used to compare a value with a set of values returned by a subquery.
Important Note:
EXISTS and NOT EXISTS are useful for checking if a subquery returns any rows at all, but they don't specifically compare multiple values from the subquery.