Question

State whether the following statement is True or False:

In SQL, an aggregate function returns multiple values for each column on which it is applied.

• A. True
• B. False
• C. Cannot be determined
• D. None of the above

Hint:

An aggregate function such as SUM or MAX summarises many rows into one value. Decide if that fits the statement.

Answer 1

The Correct Option is B

Step 1: Understand what an aggregate function does:
An aggregate function works on a set of rows and gives back one summary value.
Examples are SUM(), AVG(), MIN(), MAX(), COUNT().

Step 2: Apply it to a column:
Suppose a column holds the marks 40, 50 and 60.
SELECT SUM(marks) FROM student; reads all three values and returns one number, 150.
The three input values are collapsed into one output value.

Step 3: Apply it with GROUP BY:
With GROUP BY, the function runs once for each group.
Even then, each group gives exactly one value for each column the function is applied on.
So the function never returns many values for a single column in a single group.

Step 4: Check the statement:
The statement says the function returns multiple values for each column.
This is wrong, because it returns a single value.
So the statement is False.

Step 5: Why the other options are wrong:
Option 1 (True) says the opposite of the rule, so it is wrong.
Option 3 (Cannot be determined) is wrong because the behaviour of aggregate functions is fixed and known.
Option 4 (None of the above) is wrong because option 2 is correct.

Final Answer:
An aggregate function returns a single value, so the statement is False. This is option 2.