Syntax
VAR_SAMP(expr)
Purpose
VAR_SAMP() returns the sample variance of the expr expression. When the function calculates the sample variance of an expression that contains only one 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