STDDEV_SAMP(expr)
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.
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Licensed under the Creative Commons Attribution 3.0 Unported License and the GNU Free Documentation License.
https://mariadb.com/kb/en/stddev_samp/