Oracle Database Administration I — Question 9

Which statement is true about aggregate functions?

Answer options

• A. Aggregate functions can be nested to any number of levels
• B. The AVG function implicitly converts NULLS to zero
• C. Aggregate functions can be used in any clause of a SELECT statement
• D. The MAX and MIN functions can be used on columns with character data types

Correct answer: A

Explanation

The correct answer is A because aggregate functions can indeed be nested within each other, allowing for complex calculations. Option B is incorrect as the AVG function does not convert NULLS to zero; it simply ignores them in its calculations. Option C is false since aggregate functions are typically used in the SELECT clause and HAVING clause, not in WHERE or other clauses. Option D is wrong because while MAX and MIN can be applied to character data types, their behavior is not as straightforward as with numeric types.