MySQL COUNT(), AVG() and SUM() Functions

The COUNT() function returns the number of rows that matches a specified criterion.

COUNT() Syntax

The AVG() function returns the average value of a numeric column.

AVG() Syntax

The SUM() function returns the total sum of a numeric column.

SUM() Syntax

Demo Database

Below is a selection from the "Products" table in the Northwind sample database:

COUNT() Example

The following SQL statement finds the number of products:

SELECT COUNT(ProductID) FROM Products;

Note: NULL values are not counted.

AVG() Example

The following SQL statement finds the average price of all products:

SELECT AVG(Price) FROM Products;

Note: NULL values are ignored.

Demo Database

Below is a selection from the "OrderDetails" table in the Northwind sample database:

SUM() Example

The following SQL statement finds the sum of the "Quantity" fields in the "OrderDetails" table:

SELECT SUM(Quantity) FROM OrderDetails;

Note: NULL values are ignored.