STDDEV function [Aggregate]

Returns the standard deviation of a set of numbers.

STDDEV ( [ ALL ] expression )

expression Any numeric data type (float, real, or double precision) expression.

NULL Returns null values on one-element input sets in Sybase IQ versions prior to 12.7.

Given this data:

SELECT salary FROM employee WHERE dept_id = 300

The following statement returns the value 32617.8446712838471:

SELECT STDDEV ( 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 2.88675134594813049:

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

The formula used to calculate STDDEV is

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

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