Help with an update query

Ok so I'm not really sure how to do what I want to do, I'm not sure what to google to find out how to do it.



I want to update values in one table using values in another table. The table I want to be updated has a stock value for each product, I have a query that pulls the records from the most recent order from a composite key table.



The records I want to use to update the StockNumber values have a ProductID that corresponds to the ProductIDs in the table to be updated as well as a Quantity value that needs to be taken away from the StockNumber

Code:

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UPDATE [tblqryInvoice-Product]

INNER JOIN Products ON ([tblqryInvoice-Product].ProductName = Products.ProductID) AND ([tblqryInvoice-Product].Quantity = Products.StockNumber)

SET Products.StockNumber =[StockNumber]-[Quantity];

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This update sql bit that I managed to gleam from a tutorial website and somewhat adapt produces the message "you are about to update 0 records" when I run the query

Help with an update query