You can calculate the variance in SQL:
create table t (row int);
insert into t values (1),(2),(3);
SELECT AVG((t.row - sub.a) * (t.row - sub.a)) as var from t,
(SELECT AVG(row) AS a FROM t) AS sub;
0.666666666666667
However, you still have to calculate the square root to get the standard deviation.
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