SQL Aggregate Functions

A function that calculates a single value after applying a set of values is known as an aggregate function.

The GROUP BY clause of the SELECT statement is frequently used in conjunction with aggregate functions. The result-set is divided into groups of values via the GROUP BY via clause, and each group can have a single value returned by using the aggregate function.

The SQL aggregation functions that are most frequently used are:

• MIN() – returns the smallest value within the selected column
• MAX() – returns the largest value within the selected column
• COUNT() – returns the number of rows in a set
• SUM() – returns the total sum of a numerical column
• AVG() – returns the average value of a numerical column

With the exception of COUNT(), aggregate functions disregard null values.

The aforementioned aggregate functions will be covered in the upcoming chapters.