As you know, Power BI won't allow part of formula highlighted in red. I have seen some solutions for sales forecast while googling, but I'm unable to match their solutions with my case, as I use values from other tables which make this case somehow different. Can someone help?
Thanks @amitchandak for your response. Bad news is that my table is a cross join between two other tables one of which is totally created by DAX (GENERATESERIES) and the other is a calculated table based on another table. I cannot take this joint table to Power Query, AFAIK. So I need a pure-DAX way to accomplish this.