How to Calculate Measure and Relative Table Columns

[Masatoshi]

I am looking for a way to calculate the following using two tables that have a many-to-one relationship, but I can't find it. Can you please provide me with a DAX that can solve this?
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Relationships
- Many: 'Sales' table
- 1: 'Operation' table

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The formula I would like to achieve
Subtract the 'Operation' table cost for the same day from the following measure you want to create in the 'Sales' table = margin

Daily_Amount = CALCULATE(
SUM(Sales[Amount]),
ALLSELECTED(Sales[Item])
)

However, using the RELATED function will result in an error, probably because there is no row context.

Margin = [Daily_Amount] - RELATED('Operation'[Cost])

Margin = [Daily_Amount] - RELATED('Operation'[Cost])

Error message
The column 'Operation[Cost]' either doesn't exist or doesn't have a relationship to any table available in the current context.

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Thank you for your cooperation.

[Anonymous · Accepted solution]

Hi @Masatoshi ,

According to your description, here are my steps you can follow as a solution.

(1) My test data is the same as yours.

(2) We can create a measure. 

Margin = 
var _cost = LOOKUPVALUE(Operation[Cost],'Operation'[Date],MAX('Sales'[Date]))
return 'Sales'[Daily_Amount]-_cost

(3) Then the result is as follows.

Best Regards,

Neeko Tang

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