16. Missing Parts

SELECT q.PartId,
       q.Description,
       q.NeededQty AS [Required],
       q.StockQty AS [In Stock],
       '0' AS Ordered
 FROM(
            SELECT j.JobId,
               p.PartId,
               p.Description,
               pn.Quantity AS NeededQty,
               p.StockQty,
               op.Quantity,
               o.Delivered,
               j.STATUS FROM Parts AS p
        LEFT JOIN OrderParts AS op ON op.PartId = p.PartId
        LEFT JOIN PartsNeeded AS pn ON pn.PartId = p.PartId
        LEFT JOIN Jobs AS j ON j.JobId = pn.JobId
        LEFT JOIN Orders AS o ON o.JobId = j.JobId
        WHERE j.STATUS <> 'Finished'
        OR ((p.StockQty - pn.Quantity) < 0 )
        AND Delivered = 0) AS q
        WHERE q.Delivered IS NULL
        AND q.StockQty - q.NeededQty < 0
        ORDER BY q.PartId