VAR_SAMP

Declaration

VAR_SAMP(expr)

Description

Returns the sample variance of expr. If the expression has only one value, the function returns NULL.

The function returns NULL if no rows match the condition.

Examples

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 VAR_SAMP(salary) FROM employees;
+-----------------------------------------------+
| VAR_SAMP(salary)                              |
+-----------------------------------------------+
| 30318181.818181818181818181818181818181818181 |
+-----------------------------------------------+
1 row in set (0.001 sec)