Yea that's the one I was aiming for, but there's still that thing with having to generate accounting records. So as I mentioned every movement would be represented in it's corresponding table (sale, buy, transfer), the common history table, and the accounting table, that's 3 places. If they want to cancel something, I would have to clean up all this. Probably I'd insert a record in the history table opposite to the original instead of deleting the original.

It seems like overkill at first, but thinking then again each one of this representations has it's own purpose. I guess the accounting part is what makes it seem like just one too many representations... Or perhaps I could just use the accounting records as my common history table. The only thing is that not all records would be directly related with increasing / decreasing of my on-hand inventory, I would have to pick-up the ones that are, either by the actual account or maybe a units field... then again I need coffee :)