Oracle® Database SQL Reference 10g Release 2 (10.2) Part Number B14200-01 |
|
|
View PDF |
Syntax
Purpose
STDDEV_POP
computes the population standard deviation and returns the square root of the population variance. You can use it as both an aggregate and analytic function.
This function takes as an argument any numeric datatype or any nonnumeric datatype that can be implicitly converted to a numeric datatype. The function returns the same datatype as the numeric datatype of the argument.
This function is the same as the square root of the VAR_POP
function. When VAR_POP
returns null, this function returns null.
Aggregate Example
The following example returns the population and sample standard deviations of the amount of sales in the sample table sh.sales
:
SELECT STDDEV_POP(amount_sold) "Pop", STDDEV_SAMP(amount_sold) "Samp" FROM sales; Pop Samp ---------- ---------- 896.355151 896.355592
Analytic Example
The following example returns the population standard deviations of salaries in the sample hr.employees
table by department:
SELECT department_id, last_name, salary, STDDEV_POP(salary) OVER (PARTITION BY department_id) AS pop_std FROM employees; DEPARTMENT_ID LAST_NAME SALARY POP_STD ------------- ------------------------- ---------- ---------- 10 Whalen 4400 0 20 Hartstein 13000 3500 20 Goyal 6000 3500 . . . 100 Sciarra 7700 1644.18166 100 Urman 7800 1644.18166 100 Popp 6900 1644.18166 110 Higgens 12000 1850 110 Gietz 8300 1850