Which value does AVG actually divide by?

Question

Accepted Answer

AVG sums all non-NULL values and divides by the count of non-NULL values. (80 + 90 + 70) / 3 = 240 / 3 = 80. AVG also ignores NULLs - a NULL row does not count toward either the sum or the divisor. '85' catches anyone who averages only two of the three rows, dropping the lowest: (80 + 90) / 2. '90' catches anyone who confuses AVG(score) with MAX(score) - the highest value in the column. '240' catches anyone who returns the raw SUM without dividing by the row count.

id	score
1	80
2	90
3	70