VARIANCE

Purpose

This function returns the variance of expr within a window or group of rows. This equates to the following formula:

formula - variance

Syntax

variance::=

Usage Notes

  • With DISTINCT, the function considers duplicate values of expr only once. It considers all occurrences with ALL. If the function contains neither ALL nor DISTINCT, the default is ALL.
  • If a window or group has only one row, then the result of this function is 0.

Examples

Aggregate Function

Copy 
SELECT 
    department, 
    VARIANCE(current_salary) VARIANCE
FROM employee_table GROUP BY department;
Result
DEPARTMENT VARIANCE
ACCOUNTS 1.125e+08
HR 2.0625e+08

Analytic Function

Copy 
SELECT     
    id, department, hire_date, current_salary, 
    VARIANCE(current_salary) OVER (PARTITION BY department ORDER BY hire_date) VARIANCE 
FROM employee_table ORDER BY department, hire_date;
Result
ID DEPARTMENT HIRE_DATE CURRENT_SALARY VARIANCE
2005 ACCOUNTS 2013-01-01 80000 0
2003 ACCOUNTS 2015-07-01 80000 0
2002 ACCOUNTS 2017-01-01 65000 56250000
2004 ACCOUNTS 2017-01-01 70000 56250000
2001 ACCOUNTS 2018-07-01 55000 1.125e+08
1003 HR 2014-01-01 90000 0
1002 HR 2016-01-01 70000 1.3333333e+08
1004 HR 2016-01-01 70000 1.3333333e+08
1001 HR 2018-01-01 55000 2.0625e+08