Hi @Thimios,
It would be great if we can have a look at your model and the tables. But try this anyway :
-
reate a key in both tables : Sales and UNIT COST to link both.
Year&Month&SKU. -
Create a relationship between the two using that key.
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Add a calculated culumns that gets the unit cost from the UNIT COST table into Sales table (Using RELATED function).
-
Then you can create a measure of your cost :
`Total Cost = SUMX (Sales, Qty * Unit Cost )`