Which of the following set of operations is a valid set of aggregate operations in SQL ?

Question

Accepted Answer

The correct option is (1):
Aggregate functions in Structured Query Language (SQL) are a class of functions specifically designed to perform a calculation on a set of rows and return a single, summarized value. The set **COUNT, MAX, AVG, SUM** represents the core, foundational aggregate functions universally supported in SQL. **COUNT()** is used to count the number of rows or non-NULL values in a column. **MAX()** and its counterpart **MIN()** retrieve the largest and smallest values, respectively, from a group of data. Finally, **AVG()** calculates the arithmetic mean, and **SUM()** calculates the total sum of values in a numeric column. These operations are essential tools for data analysis, reporting, and deriving business intelligence from a database.

The incorrect option is (2):
Option 2 (MAX, AVG, SUM, SELECT) is an invalid set because **SELECT** is the primary command used to initiate a data retrieval query in SQL. It is a Data Manipulation Language (DML) statement that defines which data to display, not an aggregate function that performs a calculation on a group of values. Although the other three terms (MAX, AVG, SUM) are valid aggregate functions, the inclusion of the general SELECT statement makes the entire option incorrect.

The incorrect option is (3):
Option 3 (UNION, COUNT, MIN, DESC) is incorrect due to the inclusion of **UNION** and **DESC**. **UNION** is classified as a set operator, whose sole purpose is to combine the result sets of two or more SELECT statements. It does not perform an aggregation or calculation on a column within a table. Furthermore, **DESC** (short for DESCENDING) is a keyword used with the ORDER BY clause to specify a sort order, making it a presentation or sorting specifier, not an aggregate function.

The incorrect option is (4):
Option 4 (AVG, MIN, MAX, ASC) is incorrect because **ASC** (short for ASCENDING) is a keyword used to specify the sorting order in the ORDER BY clause of a query. Like its counterpart DESC, it dictates how the final result set should be presented (from smallest to largest) rather than performing a calculation to collapse multiple rows into a single summary figure. Therefore, since ASC is a sorting keyword and not a calculating function, this set is not a valid list of aggregate operations.