Syntax
VAR_SAMP([ALL] expr) OVER over_clause
Purpose
VAR_SAMP() returns the sample variance of the expr expression.
If no matching row is found, it returns NULL.
Examples
obclient> 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;
obclient> SELECT LAST_NAME,SALARY,VAR_SAMP(SALARY) OVER(ORDER BY HIREDATE) AS DEVISION FROM EMPLOYEES WHERE MANAGER_ID = 100;
+-----------+--------+-----------------------------------------------+
| LAST_NAME | SALARY | DEVISION |
+-----------+--------+-----------------------------------------------+
| RAPHAELY | 1700 | NULL |
| ERRAZURIZ | 1400 | 45000 |
| RAPHAELY | 1700 | 30000 |
| DE HAAN | 11000 | 22110000 |
| PARTNERS | 14000 | 36783000 |
| HARTSTEIN | 14000 | 40200000 |
| WEISS | 13500 | 38991428.571428571428571428571428571428571428 |
| RUSSELL | 13000 | 36318392.857142857142857142857142857142857142 |
+-----------+--------+-----------------------------------------------+
8 rows in set