SQL•SQL Tutorial

SQL Aggregate Functions

Overview

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.

SQL SELECT TOP, LIMIT and FETCH FIRST

SQL MIN() F unction