STDDEV_POP [analytic]

Evaluates the statistical population standard deviation for each member of the group.

Computes the statistical population standard deviation and returns the square root of the population variance within a window. The STDDEV_POP() return value is the same as the square root of the VAR_POP() function:

STDDEV_POP( expression ) = SQRT(VAR_POP( expression ))

When VAR_POP returns null, STDDEV_POP returns null.

Behavior type

Immutable

Syntax

STDDEV_POP ( expression ) OVER (
    [ window-partition-clause ]
    [ window-order-clause ]
    [ window-frame-clause ] )

Parameters

expression
Any NUMERIC data type or any non-numeric data type that can be implicitly converted to a numeric data type. The function returns the same data type as the numeric data type of the argument.
OVER()
See Analytic Functions.

Examples

The following example returns the population standard deviations of salaries in the employee dimension table by job title Assistant Director:

=> SELECT employee_last_name, annual_salary,
       STDDEV_POP(annual_salary) OVER (ORDER BY hire_date) as "stddev_pop"
   FROM employee_dimension WHERE job_title =  'Assistant Director';
 employee_last_name | annual_salary |    stddev_pop
--------------------+---------------+------------------
 Goldberg           |         61859 |                0
 Miller             |         79582 |           8861.5
 Goldberg           |         74236 | 7422.74712548456
 Campbell           |         66426 | 6850.22125098891
 Moore              |         66630 | 6322.08223926257
 Nguyen             |         53530 | 8356.55480080699
 Harris             |         74115 | 8122.72288970008
 Lang               |         59981 | 8053.54776538731
 Farmer             |         60597 | 7858.70140687825
 Nguyen             |         78941 | 8360.63150784682

See also