AntDB-Oracle Compatibility Developer’s Manual P3–61

STDDEV_SAMP

This function calculates the cumulative sample standard deviation and returns the square root of the overall variable with the same return value as the square root of the VAR_POP function.

Example:

begin;
CREATE TABLE employees (manager_id INT,last_name varchar(50),hiredate varchar(50),SALARY INT);
INSERT INTO employees VALUES(100, 'Raphaely', '2017-07-01', 1700);
INSERT INTO employees VALUES(100, 'De Haan', '2018-05-01',11000);      
INSERT INTO employees VALUES(100, 'Errazuriz', '2017-07-21', 1400);
INSERT INTO employees VALUES(100, 'Hartstein', '2019-05-01',14000);     
INSERT INTO employees VALUES(100, 'Raphaely', '2017-07-22', 1700);
INSERT INTO employees VALUES(100, 'Weiss',  '2019-07-11',13500);     
INSERT INTO employees VALUES(100, 'Russell', '2019-10-05', 13000);
INSERT INTO employees VALUES(100, 'Partners',  '2018-12-01',14000);     
INSERT INTO employees VALUES(200, 'Ross',  '2019-06-11',13500);     
INSERT INTO employees VALUES(200, 'Bell', '2019-05-25', 13000);
INSERT INTO employees VALUES(200, 'Part',  '2018-08-11',14000);
COMMIT;
SELECT manager_id, last_name, hiredate, salary,STDDEV_SAMP(salary) OVER (PARTITION BY manager_id 
ORDER BY hiredate ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS cum_sdev FROM employees ORDER BY manager_id, last_name, hiredate, salary, cum_sdev;

 MANAGER_ID | LAST_NAME |  HIREDATE  | SALARY |     CUM_SDEV      
------------+-----------+------------+--------+--------------------
        100 | De Haan   | 2018-05-01 |  11000 | 4702.127178203499
        100 | Errazuriz | 2017-07-21 |   1400 |  212.132034355964
        100 | Hartstein | 2019-05-01 |  14000 | 6340.346993658943
        100 | Partners  | 2018-12-01 |  14000 | 6064.899009876422
        100 | Raphaely  | 2017-07-01 |   1700 |                  
        100 | Raphaely  | 2017-07-22 |   1700 |  173.205080756888
        100 | Russell   | 2019-10-05 |  13000 | 6026.474330580265
        100 | Weiss     | 2019-07-11 |  13500 |  6244.31169717116
        200 | Bell      | 2019-05-25 |  13000 |  707.106781186548
        200 | Part      | 2018-08-11 |  14000 |                  
        200 | Ross      | 2019-06-11 |  13500 |               500
(11 rows)