Getting ambiguity error for a inventory SQL query where two fields should be equal to make the calculation. MS-ACCESS

Question

Having this simple group of tables, I would like to make an inventory discriminating equal products that came from different providers, but I'm getting an "ambiguity error" running a query I though it would work. I don't know how to solve this.

Here's the query I tried:

SELECT tblProducts.product_Name, 
       tblProviders.provider, 
       Nz(Sum(tblIntakes.intake_QTY),0)-
       Nz(Sum(tblExits.exit_QTY)) AS Stock

FROM tblProviders, 
     (tblProducts LEFT JOIN 
     tblExits 
     ON tblProducts.product_ID = tblExits.product_ID
     ) LEFT JOIN 
     tblIntakes 
     ON tblProducts.product_ID = tblIntakes.product_ID

GROUP BY tblProducts.product_Name, tblProviders.provider;

Answer 1

You may use subqueries in this case:

SELECT
  tblProducts.product_Name,
  tblProviders.provider,
  Nz((
    SELECT SUM(intake_QTY)
    FROM tblIntakes
    WHERE
      tblIntakes.product_ID = tblProducts.product_ID AND
      tblIntakes.provider_ID = tblProviders.provider_ID
  ), 0) -
  Nz((
    SELECT SUM(exit_QTY)
    FROM tblExits
    WHERE
      tblExits.product_ID = tblProducts.product_ID AND
      tblExits.provider_ID = tblProviders.provider_ID
  ), 0) AS Stock
FROM tblProviders, tblProducts;