Counting problem in table

[darroyo_telcomu]

Hi!

I have a products database table with two columns:
* Date when the product was added to stock
* Serial number of the product

Now I want a Qlik table that shows:
* MonthYear
* How many products were in stock each day, I mean, how many products with an "Add Date" lower than the date of the table.

I have been testing things like:
if( MonthYear <= max(MonthYear), count(serialnumber))
count( {< MonthName={"<=$(<=Date(Date#(max(MonthName), 'MMM-YY'), 'MMM-YY'))"} >} serialnumber)
...

The problem is that the MonthYear column affects the Count column, so the Count column only takes the records for the corresponding MonthYear value. I would need a count about every MonthYear value, not just the MonthYear of that row.

I know this is not the best explanation ever, but thanks anyway for your support!

[vinieme12]

can you post some sample data that best represents your actual data

[darroyo_telcomu]

Yes, sure!

I attach here an image. The left table is data from source database. The table in the right is what I would like to show in Qlik, using set analysis for the "active items" column.