Which of the following is not a valid aggregate function ?

Question

Accepted Answer

The correct option is (2):
The correct answer is COMPUTE because it is not recognized as a standard SQL aggregate function. Aggregate functions are essential SQL tools designed to perform a calculation on a set of values (a column) and return a single summary result. The internationally accepted set of core aggregate functions includes AVG, COUNT, MIN, MAX, and SUM. The term `COMPUTE` was a *clause* found in older, proprietary versions of SQL (specifically Transact-SQL in Microsoft SQL Server), which was used to generate summary rows (like subtotals) in a result set, and it did not function as a standard aggregate function. This `COMPUTE` clause has since been largely deprecated in favor of standard functions used with the `GROUP BY` clause and its extensions like `ROLLUP` or `CUBE`.

The incorrect option is (1):
COUNT is a fundamental and universally valid SQL aggregate function. Its purpose is to return a single value representing the number of rows in a table or the count of non-NULL values in a specified column, which is essential for data validation and basic statistical reporting. It is used in two primary forms: `COUNT(*)`, which counts all rows, and `COUNT(column)`, which counts non-null entries in that column.

The incorrect option is (3):
SUM is a standard and valid SQL aggregate function that is widely supported across all relational database management systems. This function is used to calculate the total arithmetic sum of all numerical values within a designated column. It is a core function for financial and quantitative analysis, allowing users to quickly determine totals for fields like sales, cost, or inventory amount.

The incorrect option is (4):
MAX is a standard and valid SQL aggregate function, which is used to find the largest single value in a set of rows for a specified column. It is a powerful tool for identifying extreme values, such as the highest salary, the latest transaction date, or the alphabetically last name in a group. Its counterpart, MIN, is also a standard aggregate function.