VAR_SAMP

Syntax

var_samp::=
Description of var_samp.gif follows

Description of the illustration var_samp.gif

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 datatype or any nonnumeric datatype that can be implicitly converted to a numeric datatype. The function returns the same datatype as the numeric datatype of the argument.

See Also:

Table 2-11, "Implicit Type Conversion Matrix" 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(expr2) - SUM(expr)2 / COUNT(expr)) / (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)
----------------
      15283140.5

Analytic Example

Please refer to the analytic example for VAR_POP .