Measure for sum of open positions in accounting (two date columns in source) - excel

Question

I would like to calculate the sum of open positions in a receivables account. The entries in the accounting system provide three relevant columns in the source table to that end:
booking date
due (=pay) date
amount due
I would like to have a measure that I can use for a graph, showing the total of all open positions on each day.
An open position is an amount booked with a booking date before "today" and with a due date after "today".
I tried the following approach in my Power Pivot model (with three calendar tables):
booking date related to "calendar table 1"
due date related to "calendar table 2"
Date columns of "calendar table 1" and "calendar table 2" related to a third "calendar table main"
For that formula I am getting an error message:
Hm, not sufficiently proficient in PowerPivot to solve this problem.

Answer 1

SumAmt:=
SUM( Source_Table[Amount] )
OpenPositions:=
CALCULATE(
[SumAmt]
;FILTER(
VALUES( Source_Table[Booking_Date] )
;Source_Table[Booking_Date] < MAX( Calendar_Main[Calendar_Date] )
)
;FILTER(
VALUES( Source_Table[Due_Date] )
;Source_Table[Due_Date] > MAX( Calendar_Main[Calendar_Date] )
)
)
Your error is pretty self-explanatory. If you use a direct column reference in CALCULATE() you can only reference a single column. You are referencing two, Calendar_Main[Calendar_Date] and either Source_Data[Booking_Date] or Source_Data[Due_Date]. This is simply not allowed, so it throws the error.
The workaround is simply to wrap complex filtering logic in table expressions and use those as arguments to CALCULATE(). Pretty much, unless you are hard-coding a literal predicate for a single column, you should be using some sort of table expression, like FILTER(), as your arguments to CALCULATE().
What we do is call FILTER() twice to check the dates. We use MAX()s because we cannot perform comparisons between column references, we need to perform inequality comparisons between scalars.
Since we're FILTER()ing over Source_Data[Booking_Date] and Source_Data[Due_Date], the references to these are evaluated in row context and refer to the value of the current row in FILTER()'s iteration. The reference to Calendar_Main[Calendar_Date] is just a column reference, so we wrap it in MAX() to get a scalar value for our inequality. The MAX() refers to the current filter context coming in from the pivot table, which would be the current row label or column label.
If you aggregate to the month level, this will give you essentially the closing balance, since we're using MAX()s. At the month level the value will be identical to that on the last date of the month.
Finally, with the inequalities you've set up, you're ignoring anything opened on the current day or due on the current day. I'd expect you want [Booking_Date] <= [Calendar_Date] and [Due_Date] > [Calendar_Date].