又学了查了一下帮助:
VARIANCE
Syntax
VARIANCE([DISTINCT|ALL]x)
Purpose
Returns variance of x, a number. Oracle calculates the variance of x using this formula:
where:
xi is one of the elements of x.
n is the number of elements in the set x. If n is 1, the variance is defined to be 0.
Example
SELECT VARIANCE(sal) "Variance"
FROM emp;
Variance
----------
1389313.87
VARIANCE
Syntax
VARIANCE([DISTINCT|ALL]x)
Purpose
Returns variance of x, a number. Oracle calculates the variance of x using this formula:
where:
xi is one of the elements of x.
n is the number of elements in the set x. If n is 1, the variance is defined to be 0.
Example
SELECT VARIANCE(sal) "Variance"
FROM emp;
Variance
----------
1389313.87
to shahand(死磕) :俺是初学者,哪里有比较好的帮助文档呢。