The SQL AVG() Function
The AVG() function returns the average value of a numeric column.
Example
Find the average price of all products:
SELECT AVG(Price)
FROM Products;
Note: NULL values are ignored.
Syntax
SELECT AVG(column_name) FROM table_name WHERE condition;
Demo Database
Below is a selection from the Products table used in the examples:
| 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 |
Add a WHERE Clause
You can add a WHERE clause to specify conditions:
Example
Return the average price of products in category 1:
SELECT AVG(Price) FROM Products WHERE CategoryID = 1;
Use an Alias
Give the AVG column a name by using the AS keyword.
Example
Name the column “average price”:
SELECT AVG(Price) AS [average price] FROM Products;
Higher Than Average
To list all records with a higher price than average, we can use the AVG() function in a sub query:
Example
Return all products with a higher price than the average price:
SELECT * FROM Products
WHERE price > (SELECT AVG(price) FROM Products);
Use AVG() with GROUP BY
Here we use the AVG() function and the GROUP BY clause, to return the average price for each category in the Products table:
Example
SELECT AVG(Price) AS AveragePrice, CategoryID
FROM Products
GROUP BY CategoryID;