Syntax
------ 
STDDEV_SAMP(expr)
 
Description
----------- 
Returns the sample standard deviation of expr (the square
root of VAR_SAMP()).
 
It is an aggregate function, and so can be used with the
GROUP BY clause.
 
From MariaDB 10.2.2, STDDEV_SAMP() can be used as a window
function.
 
STDDEV_SAMP() returns NULL if there were no matching rows.
 

 
 
 
 
 
 
 

URL: https://mariadb.com/kb/en/stddev_samp/