SQL Aggregate Functions

SQL Aggregate Functions

An aggregate function is a function that performs a calculation on a set of values, and returns a single value.

Aggregate functions are often used with the GROUP BY clause of the SELECT statement. The GROUP BY clause splits the result-set into groups of values and the aggregate function can be used to return a single value for each group.

The most commonly used SQL aggregate functions are:

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

Aggregate functions ignore null values (except for COUNT(*)).

We will go through the aggregate functions above in the next chapters.