Syntax
VARIANCE([ ALL ] expr) OVER (analytic_clause)
Purpose
VARIANCE() returns the population standard variance of the expr expression. It is an alias for VAR_POP().
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,VARIANCE(SALARY) OVER(ORDER BY HIREDATE) AS DEVISION FROM EMPLOYEES WHERE MANAGER_ID = 100;
+-----------+--------+-------------------+
| LAST_NAME | SALARY | DEVISION |
+-----------+--------+-------------------+
| RAPHAELY | 1700 | 0 |
| ERRAZURIZ | 1400 | 22500 |
| RAPHAELY | 1700 | 20000 |
| DE HAAN | 11000 | 16582500 |
| PARTNERS | 14000 | 29426400 |
| HARTSTEIN | 14000 | 33500000 |
| WEISS | 13500 | 33421224.48979592 |
| RUSSELL | 13000 | 31778593.75 |
+-----------+--------+-------------------+
8 rows in set
