thanks for the links, I have been reading those kind of Database Design material, but when it comes to actual implementation, it is still as difficult.

yes, a good idea is to the Sales/Revenue field put into another table Sale. Then I would need to associate the Sale table with the Machine table, and it seems to me it should be a Many-To-Many relationship.

I would need to get the overall Design Database architecture right, else things would get more messy, as the database grows to include more complex stuffs. For the present, I would need to extract information, as per machine basis.