Oracle8i SQL Reference Release 2 (8.1.6) A7698901 

Functions, 117 of 121
For information on syntax and semantics, see "Analytic Functions".
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.
The expr is a number expression, and the function returns a value of type NUMBER
. If the function is applied to an empty set, it returns null. The function makes the following calculation:
(SUM(expr^{2})  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.
The following example returns the sample variance of the salaries in the EMP
table.
SELECT VAR_SAMP(sal) FROM emp; VAR_SAMP(SAL)  1398313.87
See the example at "VAR_POP".

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