count if I have 12 months before the selected

[#1]

Hi Everyone...

I need to know if a product has been in sold 12 months before the month selected.

For example, my table is:

Product	Year&Month
1	201208
1	201209
1	201210
1	201211
1	201212
1	201301
1	201302
1	201303
1	201304
1	201305
1	201306
1	201307

In this situation if I choose the Year&Month 201307 the product 1 will have the count of 12 months before.

But in some case one month is not in the list, let say 201304 is not in the table, then I will have a count of 11 before if a select the Year&Month 201307.

Can I put this in a expression or script?

Thanks

[#2]

Can you post an example QVW with the script in?

[Gysbert_Wassenaar]

See attached qvw.

[#4]

Hi gysbert...

Nice example, i think it will be ok with a modification.

how can I get filter the products that just have de 12 months consecutive before.

In other words, When I click the YearMonth just let the products that have the 12 months before in the table.

thanks

[Gysbert_Wassenaar]

Try:

='Count: ' & count({<YearMonth=,Product={"=count({<YearMonth=,YMNo={'>=$(=max(YMNo)-12)<$(=max(YMNo))'}>}distinct YearMonth)=12"}>}distinct Product)