MySQL COUNT, AVG, SUM

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

The number of rows that satisfy a certain criterion is returned by the COUNT() method.

				
					SELECT COUNT(column_name)
FROM table_name
WHERE condition;

The average value of a numerical column is returned by the AVG() function.

				
					SELECT AVG(column_name)
FROM table_name
WHERE condition;

The total sum of a numeric column is returned by the SUM() function.

				
					SELECT SUM(column_name)
FROM table_name
WHERE condition;

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

The following SQL statement finds the number of products:

				
					SELECT COUNT(ProductID)
FROM Products;

Note: NULL values are not counted.

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

				
					SELECT AVG(Price)
FROM Products;

Note: NULL values are ignored.

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

OrderDetailID	OrderID	ProductID	Quantity
1	10248	11	12
2	10248	42	10
3	10248	72	5
4	10249	14	9
5	10249	51	40

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.