T-SQL Tutorial

SQL Aggregate functions

Aggregate functions perform a calculation on a set of values and return a single value. The SQL Aggregate functions are: AVG, SUM, MAX, MIN, COUNT.


SQL AVG function returns the average value.

select avg(price) from courses;
select name, price
from courses
group by name, price
having avg(price) > 70;


SQL SUM function returns the sum of all values.

select sum(price) from courses;
select sum(price)
from courses
where price > 50;


SQL MAX function returns the max value.

select max(price) from courses;
select max(price)
from courses
where price < 70;


SQL MIN function returns the min value.

select min(price) from courses;
select min(price)
from courses
where price > 70;


SQL COUNT function returns the number of rows returned by a query.

select count(*) from courses;
select count(*), price
from courses
group by price
having count(*) = 2;