The gini function calculates the Gini coefficient. The Gini coefficient is a measure of unequal distribution. A return value of 0 signifies signals that all values are equal. The return values approaches 1 if all values but one are zero.
The syntax of the function is
x are the values for which the Gini coefficient shall be calculated.
Null values are ignored.
If the number of values is zero, the function returns null.
w is the frequency with which the value x occurs. If no frequency is provided, the frequency is assumed to be 1.
SELECT gini(salary) FROM persons;