VAR_POP

Returns the population variance, that is, the mean squared deviation from the mean.

MySQL 8.1

VAR_POP(expr)

Parameters

A floating-point number (DOUBLE); NULLs are ignored; 0 for a single value, NULL for an empty set

MySQL 8.1

SELECT ROUND(VAR_POP(delivery_time_min), 1) AS time_variance
FROM orders;

time_variance
935.7

MySQL 8.1

SELECT VAR_POP(x) AS one_value,
	VAR_SAMP(x) AS sample
FROM (
		SELECT 5 AS x
	) AS t;

one_value	sample
0	<NULL>

The sum of squared deviations is divided by the number of values. The synonym in MySQL is VARIANCE. The square root of the result equals STDDEV_POP.