STDDEV [Analytic]
Computes the statistical sample standard deviation of the current row with respect to the group within a window. STDDEV_SAMP
returns the same value as the square root of the variance defined for the VAR_SAMP
function:
STDDEV( expression ) = SQRT(VAR_SAMP( expression ))
When VAR_SAMP
returns NULL
, this function returns NULL
.
The nonstandard function STDDEV
is provided for compatibility with other databases. It is semantically identical to STDDEV_SAMP
.
Behavior Type
Syntax
STDDEV ( expression ) OVER ( [ window-partition-clause ] [ window-order-clause ] [ window-frame-clause ] )
Parameters
expression |
Any |
OVER()
|
Example
The following example returns the standard deviations of salaries in the employee dimension table by job title Assistant Director:
=> SELECT employee_last_name, annual_salary, STDDEV(annual_salary) OVER (ORDER BY hire_date) as "stddev" FROM employee_dimension WHERE job_title = 'Assistant Director'; employee_last_name | annual_salary | stddev --------------------+---------------+------------------ Bauer | 85003 | NaN Reyes | 91051 | 4276.58181261624 Overstreet | 53296 | 20278.6923394976 Gauthier | 97216 | 19543.7184537642 Jones | 82320 | 16928.0764028285 Fortin | 56166 | 18400.2738421652 Carcetti | 71135 | 16968.9453554483 Weaver | 74419 | 15729.0709901852 Stein | 85689 | 15040.5909495309 McNulty | 69423 | 14401.1524291943 Webber | 99091 | 15256.3160166536 Meyer | 74774 | 14588.6126417355 Garnett | 82169 | 14008.7223268494 Roy | 76974 | 13466.1270356647 Dobisz | 83486 | 13040.4887828347 Martin | 99702 | 13637.6804131055 Martin | 73589 | 13299.2838158566 ...