DAX - TOPN() in a SUMX() for multiple transactions - powerbi

Question

I need your help.
I am trying to make a calculated column which sum the sales for the last two dates (there are not sales on all dates!) for each product.
I have tried to use the calculation:
CALCULATE (
SUMX ( TOPN ( 2; 'Table'; 'Table'[date_ID] ); 'Table'[Sale] );
ALLEXCEPT ( Table; 'Table'[Product_ID] )
)
But this only works if you have one sale per date per product ID.
What do I do if there are many transactions per date and prod ID?
Below I have a table where I have (filtered) one date and one product.
Now, I have made a calculated column that sums all transactions per date and product ID (for reference).
This is
Calculated Column 2 =
CALCULATE (
SUMX ( Table; Table[Sale] );
ALLEXCEPT ( Table; 'Table'[Date]; 'Table'[Product_ID] )
)
Now comes the difficult part.
If I want to sum the transactions for the last two dates on each product, I have made the following calculation:
Calculated Column 1 =
VAR SumProd =
CALCULATE (
SUMX ( Table; Table[Sale] );
ALLEXCEPT ( Table; Table[Date]; Table[Product_ID] )
)
RETURN
CALCULATE (
SUMX ( TOPN ( 2; 'Table'; 'Table'[Date] ); SumProd );
ALLEXCEPT ( Table; Table[Product_ID]; Table[Date] )
)
The Problems:
The calculations sums ALL the values in each category
Example: in the table, you see "Calculated column 1"=7571200, which is 27040 * number of transactions? I only want the value 27040.
For some reason, the TOPN() doesn’t work. If I change the N_Value=2 to N_Value=3, the calculation doesn’t change?
Please, does anyone know what is wrong with my calculation?
Thanks.
Br,
Jakob

Answer 1

In your measure, SumProd is a constant that you're summing for each row in the table. This is not what you want.
I'd suggest something more like this:
Calculated Column 1 =
VAR LastTwoDates =
CALCULATETABLE (
VALUES ( Table[Date] );
TOPN ( 2; ALLEXCEPT ( Table; Table[Product_ID] ); Table[Date] )
)
RETURN
CALCULATE (
SUM ( Table[Sale] );
ALLEXCEPT ( Table; Table[Product_ID] );
Table[Date] IN LastTwoDates
)
In this, we first calculate a list of the top 2 dates associated with Product_ID and store it as a variable. Then we use that as a filter when calculating the sum of Sale.
I'm not positive this exact syntax will work, but I hope it will point you in a better direction.
It turns out my code didn't work exactly as intended. Try this instead:
Calculated Column 1 =
VAR ProductDates =
CALCULATETABLE (
VALUES ( Table1[Date] );
ALLEXCEPT ( Table1; Table1[Product_ID] )
)
VAR LastTwoDates = TOPN ( 2; ProductDates; [Date] )
RETURN
CALCULATE (
SUM ( Table1[Sale] );
ALLEXCEPT ( Table1; Table1[Product_ID] );
Table1[Date] IN LastTwoDates
)