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

The SQL COUNT(), AVG() and SUM() Functions
The COUNT() function returns the number of rows that matches a specified criteria.

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

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

COUNT() Syntax
SELECT COUNT(column_name)
FROM table_name
WHERE condition;
AVG() Syntax
SELECT AVG(column_name)
FROM table_name
WHERE condition;
SUM() Syntax
SELECT SUM(column_name)
FROM table_name
WHERE condition;
Demo Database
Below is a selection from the "Products" table in the Northwind sample database:

ProductID ProductName SupplierID CategoryID Unit Price
1 Chais 1 1 10 boxes x 20 bags 18
2 Chang 1 1 24 - 12 oz bottles 19
3 Aniseed Syrup 1 2 12 - 550 ml bottles 10
4 Chef Anton's Cajun Seasoning 2 2 48 - 6 oz jars 22
5 Chef Anton's Gumbo Mix 2 2 36 boxes 21.35