How to create a Rolling 13 months dimension and use in a bar chart?

[jim_chan]

Hi there, 

I want to create a rolling 13 months dimension , for a bar chart. but i dont know how to write the script.

Example: no is Nov 2022. so by putting this rolling 13 months, it will be Nov2021 - Nov 2022 ( 13 months right?) 

expression: sum(sales)

Please help guys!

[jim_chan]

I tried to use this expression. but it only came out 2022 jan - 2022 Nov. is wrong.

Dimension YearMonth

Expression: Sum({<YearMonth = {">=$(=AddMonths(Max(YearMonth),-12)) <=$(=Max(YearMonth))"}>} SUM_NET_SALES)

and in the loading script, it shows 

please help!

[vinieme12 · Accepted solution]

Instead of YearMonth you need to use your Datefield 

Sum({<datefield = {">=$(=Date(AddMonths(Max(datefield),-12))) <=$(=Date(Max(datefield)))"}>} SUM_NET_SALES)