STDDEV_POP function [Aggregate]

Function

Computes the standard deviation of a population consisting of a numeric-expression, as a DOUBLE.

Syntax

STDDEV_POP ( [ALL] expression )

Parameters

expression The expression (commonly a column name) whose population-based standard deviation is calculated over a set of rows.

Examples

The following statement lists the average and variance in the number of items per order in different time periods:

SELECT year( ship_date ) AS Year, quarter( ship_date )
  AS Quarter, AVG( quantity ) AS Average, 
  STDDEV_POP ( quantity ) AS Variance 
FROM sales_order_items GROUP BY Year, Quarter 
  ORDER BY Year, Quarter;

Year

Quarter

Average

Variance

2000

1

25.775148

14.2794

2000

2

27.050847

15.0270

...

...

...

...

Usage

Computes the population standard deviation of the provided value expression evaluated for each row of the group or partition (if DISTINCT was specified, then each row that remains after duplicates have been eliminated), defined as the square root of the population variance.

Computes the population standard deviation of the provided value expression evaluated for each row of the group or partition if DISTINCT was specified, then each row that remains after duplicates have been eliminated, defined as the square root of the population variance

Standards and compatibility

See also

“Analytical functions”

Chapter 4, “Using OLAP” in the Sybase IQ Performance and Tuning Guide