Computes the standard deviation of a population consisting of a numeric-expression, as a DOUBLE.
Parameter |
Description |
---|---|
expression |
The expression (commonly a column name) whose population-based standard deviation is calculated over a set of rows. |
DOUBLE
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.
SQL—Vendor extension to ISO/ANSI SQL grammar.
Sybase—Not supported by Adaptive Server Enterprise.
SELECT year( ship_date ) AS Year, quarter( ship_date ) AS Quarter, AVG( quantity ) AS Average, STDDEV_POP ( quantity ) AS Variance FROM SalesOrderItems GROUP BY Year, Quarter ORDER BY Year, Quarter;
Year |
Quarter |
Average |
Variance |
---|---|---|---|
2000 |
1 |
25.775148 |
14.2794 |
2000 |
2 |
27.050847 |
15.0270 |
... |
... |
... |
... |