AVG( [ ALL | DISTINCT ] numeric-expression )

AVG( [ ALL ] numeric-expression ) OVER ( window-spec )

window-spec : see Syntax 2 instructions in the Remarks section below

Returns the NULL value for a group containing no rows.

Returns DOUBLE if the argument is DOUBLE, otherwise NUMERIC.

This average does not include rows where the numeric-expression is the NULL value.

Syntax 2 represents usage as a window function in a SELECT statement. As such, elements of window-spec can be specified either in the function syntax (inline), or in conjunction with a WINDOW clause in the SELECT statement. See the window-spec definition provided in WINDOW clause.

For more information about using window functions in SELECT statements, including working examples, see Window functions.

For more information about specifying a window specification in an OVER clause, see Window definition: Inlining using the OVER clause and WINDOW clause.

This function can generate an overflow error, resulting in an error being returned. You can use the CAST function on numeric-expression to avoid the overflow error.

• CAST function [Data type conversion]
• SUM function [Aggregate]
• COUNT function [Aggregate]

• Aggregate functions and outer references

The following statement returns the value 49988.623200.

SELECT AVG( Salary ) FROM Employees;

The following statement returns the average product price from the Products table:

SELECT AVG( DISTINCT UnitPrice ) FROM Products;

The following statement returns an error with SQLSTATE 42W68 because the arguments of AVG contain both a quantified expression from the subquery, and an outer reference (p.Quantity) from the outer SELECT block:

select * from Products as p
where p.Quantity > ( select avg( 0.5 * p.Quantity + 0.5 * s.Quantity )
                     from SalesOrderItems as s
                     where s.ProductID = p.ProductID )