Avgw Function
The avgw function returns the the weighted average of a set of values.
The syntax of the avgw function is
avgw(x [,w])
x are the values for which the weighted average shall be calculated.
Null values are ignored.
If the number of values is zero,
the function returns null.
w are the weights. If no value is provided,
the weight is assumed to be 1.
Example
SELECT country, avgw(price, volume) FROM sales GROUP BY country;