# How to calculate weekly average in SQL

SQL COUNT(), AVG() and SUM() Functions Previous Next The SQL COUNT(), AVG() and SUM() Functions The COUNT() function returns

## SQL COUNT(), AVG() and SUM() Functions Previous Next

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

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

### COUNT() SyntaxSELECT COUNT(column_name)

FROM table_name

WHERE condition;

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

### AVG() SyntaxSELECT AVG(column_name)

FROM table_name

WHERE condition;

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

### SUM() SyntaxSELECT 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

## COUNT() Example

The following SQL statement finds the number of products:

### Example SELECT COUNT(ProductID)

FROM Products; Try it Yourself »

**Note:** NULL values are not counted.

## AVG() Example

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

### Example SELECT AVG(Price)

FROM Products; Try it Yourself »

**Note:** NULL values are ignored.

## Demo Database

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

## SUM() Example

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

### ExampleSELECT SUM(Quantity)

FROM OrderDetails;Try it Yourself »

**Note:** NULL values are ignored.

## Test Yourself With Exercises

## Exercise:

Use the correct function to return the number of records that have the Price value set to 18.SELECT (*) FROM Products Price = 18;

Submit Answer »

Start the Exercise

Previous Next