Count distinct subject by month it first appeared

[TG_12]

I have a table similiar to the below:

DateTimeRecieved	Subject	Folder
01/01/2022	Red	Square
23/01/2022	Blue	Circle
28/01/2022	Red	Square
03/02/2022	Red	Square
15/02/2022	Green	Triangle

I want to count the distinct subjects per month but only count the first occurence of the subject with the month it was recieved. I.e. Count 'Red' as 1 and only show it when I filter the month to January (If the month was filtered to Feb do not include red in the coutn of subject)

This data will be represented in a bar graph showing 'Number of subjects' by 'Folder' This graoh can then be filtered by month of DateTimeReceived

Thanks  

[TG_12]

@amitchandak  - Thanks for the response.

Is the 'Month Year sort' column to be a seperate column from 'Month Year'? 

When I try to write both these DAX in the same column I receive a syntax error. 

Thanks

[amitchandak]

@TG_12 , 2 separate columns

How to Create Sort Column and Solve Related Errors:
https://www.youtube.com/watch?v=KK1zu4MBb-c

[TG_12]

@amitchandak - Appreciate your assistance here and thank you for sharing that vid on sort columns - very informative! 

Unfortunately when using this solution the measure will still count the unique subject as '2' as it appears in 2 months.

E.g. using the following example the measure will count 'Red' in both Jan and Feb when I would only like to count 'Red' in Jan as that is when it first appeared

Month Year	Subject
Jan-2021	Red
Jan-2021	Red
Feb-2021	Red

The ideal scneario from this data example would be a count that shows the total unique subjects being = 1 which can then be filtered by month to show Jan-2021 = 1 & Feb-2021 = 0  

[Anonymous]

fJust to follow the subject

[amitchandak]

@TG_12 , create a month year column and then create meausre

column

Month Year = FORMAT([Date],"mmm-yyyy")
Month Year sort = FORMAT([Date],"yyyymm")

measure  =

countrows(Summarize(Table, Table[month], Table[Subject]))