VARIANCE function [Aggregate]

Returns the variance of a set of numbers.

VARIANCE ( [ ALL ] expression )

Given this data:

SELECT salary FROM employee WHERE dept_id = 300

The following statement returns the value 1063923790.99999994:

SELECT VARIANCE ( salary ) FROM employee
WHERE dept_id = 300

Given this data:

SELECT unit_price FROM product WHERE name = 'Tee Shirt'

The following statement returns the value 8.33333333333334327:

SELECT VARIANCE ( unit_price ) FROM product
WHERE name = 'Tee Shirt'

The formula used to calculate VARIANCE is

VARIANCE returns a result of data type double precision floating point. If applied to the empty set, the result is NULL.

VARIANCE does not support the keyword DISTINCT. A syntax error is returned if DISTINCT is used with VARIANCE.