If I want to sum the percentages from April, May and June only if a column is Not Null, how would I do that?
example
Tbl 1
PK, Month
Percent
Tbl 2
FK, Month Enrolled
Qty of Rx in the 1st month enrolled
Qty of Rx in 2nd qtr
Base (if Qty of Rx in 2nd Qtr is null then Qty of Rx in 1st month...