MySQL COUNT, AVG , SUM

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

The COUNT() function returns the number of rows that fulfill a specified condition.

SELECT COUNT(column_name)
FROM table_name
WHERE condition;

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

SELECT AVG(column_name)
FROM table_name
WHERE condition;

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

SELECT SUM(column_name)
FROM table_name
WHERE condition;

Here is a selection from the “Products” table in the Northwind sample database:

The following SQL statement determines the number of products:

SELECT COUNT(ProductID)
FROM Products;

Note: NULL values are not included in the count.

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

SELECT AVG(Price)
FROM Products;

Note: NULL values are not considered in the calculation.

Here is a selection from the “OrderDetails” table in the Northwind sample database:

The following SQL statement calculates the total sum of the “Quantity” fields in the “OrderDetails” table:

SELECT SUM(Quantity)
FROM OrderDetails;

Note: NULL values are not taken into account.