STDEVP function is used to perform statistical standard deviation for the population of all values in the given expression.It can be used with numeric type columns only. Null values are ignored while performing deviation for the population of an expression.

Syntax of STDEVP function :

STDEVP (expression )

Expression is avalid expression in sql sever of type numeric except bit data type. 

Return type of STDEVP function is float. 

Example of STDEVP function :

SELECT STDEVP(Royalty)

FROM    Products

Output

19.0176329973953

Above example returns standard deviation for population of royalty column.