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 within the selected columnMAX()
- returns the largest value within the selected columnCOUNT()
- returns the number of rows in a setSUM()
- returns the total sum of a numerical columnAVG()
- 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.