Returns

COUNT

of all rows of the

students

table

SELECT COUNT(*) AS students_count
FROM students

Returns

minimum

points from

students

table

SELECT MIN(points) AS minimum_points
FROM students

Returns

maximum

points from

students

table

SELECT MAX(points) AS maximum_points
FROM students

Returns

average

points from

students

table

SELECT AVG(points) AS average_points
FROM students

Returns

SUM

of all students points

SELECT SUM(points) AS 'sum of all points'
FROM students

Aggregate functions behaves differently when there is any number of additional columns with any of the aggregate functions in

SELECT

clause.

GROUP BY

clause is needed when there is any additional column from the table. In this example rows are grouped by

last_name

and the value that

SUM

function returns is aggregated. We get all the unique last names with its aggregated points

SELECT last_name, SUM(points) AS 'sum of all points'
FROM students
GROUP BY last_name

We can do the same for all the other aggregated functions Complete list of aggregate functions: https://dev.mysql.com/doc/refman/5.6/en/aggregate-functions.html