Merging queries on product number AND on date - powerbi

Question

For a report on bakery product performance I am trying to match the purchase price with the selling price in order to get to a product margin. The purchase price sits in a separate table and so does the selling price. Both tables contain product numbers so I am able to merge the two queries in order to get both selling price and purchase price on one line in order to compute a product margin.
The difficulty however is the fact that the selling prices and purchase prices are very subjective to change. Each line in both tables has a date field that is changing often. Therefore I would like to merge the queries in such a way that the selling price of a given product is corresponding to the purchase price of the same product, but also make sure that the date of the selling price and purchase price align.
How would I go about and do this?
Tables would look like this:
DATE - SHOP - PRODUCTNR - QUANTITY SOLD - TOTAL SALES - SELLING PRICE PER PRODUCT
DATE - PRODUCTNR - PURCHASE PRICE PER PRODUCT

Answer 1

You need to add a new column consisting of the [PRODUCTNR] and [DATE] fields. You can use a simple concatenate operation to achieve this:
For Example:
Let's say you have such a table:
Then you need to create a new column called [CompositeKey] in the table:
CompositeKey =
[DATE] & "-" & [PRODUCTNR]
Resulting Table:
Note: I used (-) character to separate columns. You can use any others, like pipe(|), underscore(_) etc...
Now you need to do the same for your 2nd table, and create a relationship between your [CompositeKey] columns on both tables. Now It will adapt to changing dates, and you will know which is which... I hope It solves your problem.