It will depend on your data what is the best way.
If you load using data manager, it will create a YearMonth field which you can use as a dimension or create your own calendar.
You should also have a reference per order of each that you could count.
so table would have
Item YearMonth Count(OrderRef)
i am little unclear on the problem. i am assuming you want the total sold for the month
- why are you counting the transaction dates? instead of transactionid or something similar
- you seem to have a master/autocalendar - instead of using aggr - just use YearMonth as the dimension simple count function as the measure
The criteria is a bit unique here. I need to count the sold item as 1 for the day instead of total sold per day.
and with that 1 count per day, I need to summarize the total of date counted by months.
For ex. item 1 sold 18 on 2-Jan-2018. the count will become 1 for 2-Jan-2018 and so on.
I have already use the YearMonth dimension but see the monthly chart is not the sum for all items.