TSQL - Average of all values in a column that are not zero

Question

I\'m in the process of writing a report and am looking to get the average value of an age column. The problem is that not all rows have an age.

If the values for the

Answer 1

SELECT

    AVG (CASE WHEN Value <> 0 THEN Value ELSE NULL END)
    ....

AVG won't take into account NULL values. Or this

    AVG (NULLIF(Value, 0))