Syntax
VAR_SAMP(expr)
Purpose
You can call this function to return the sample variance of expr. When the function calculates the sample variance of an expression that contains a value, it returns NULL.
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 VAR_SAMP(salary) FROM employees;
+-----------------------------------------------+
VAR_SAMP(salary)
+-----------------------------------------------+
30318181.818181818181818181818181818181818181
+-----------------------------------------------+
1 row in set (0.00 sec)