Reading Data

Aggregate Functions

Aggregate functions calculate one value from many rows.

SELECT COUNT(*) FROM students;          -- 3
SELECT AVG(marks) FROM students;        -- 85
SELECT MAX(marks), MIN(marks) FROM students;
SELECT SUM(amount) FROM orders WHERE status = 'paid';

Function	Returns
`COUNT()`	Number of rows
`SUM()`	Total
`AVG()`	Average
`MIN()` / `MAX()`	Smallest / largest