1. SQL Language Reference
  2. Functions
  3. VAR_SAMP

VAR_SAMP

Syntax

Description of var_samp.eps follows
Description of the illustration var_samp.eps

See Also:

"Analytic Functions" for information on syntax, semantics, and restrictions

Purpose

VAR_SAMP returns the sample variance of a set of numbers after discarding the nulls in this set. You can use it as both an aggregate and analytic function.

This function takes as an argument any numeric data type or any nonnumeric data type that can be implicitly converted to a numeric data type. The function returns the same data type as the numeric data type of the argument.

See Also:

Table 2-8 for more information on implicit conversion

If the function is applied to an empty set, then it returns null. The function makes the following calculation:

(SUM(expr - (SUM(expr) / COUNT(expr)))2) / (COUNT(expr) - 1)

This function is similar to VARIANCE, except that given an input set of one element, VARIANCE returns 0 and VAR_SAMP returns null.

See Also:

"About SQL Expressions" for information on valid forms of expr and "Aggregate Functions"

Aggregate Example

The following example returns the sample variance of the salaries in the sample employees table. 

SELECT VAR_SAMP(salary) FROM employees;

VAR_SAMP(SALARY)
----------------
      15284813.7

Analytic Example

Refer to the analytic example for VAR_POP.