Automatically Add new row of data

[wdrspens]

I have a table of 12 item quantities.
Every so often I either take away a quantity of some items or add a quantity of some items (seldom all items).
Is it possible to automatically create a new row of the quantity of items by either adding to the previous row, or subtracting from the previous row, depending upon whether the row is an add or subtract row?
This using an ID identifier I have a row consisting of:
ID Item1 Item2 Item3 .... Item12
1 5 8 3 15 - This is the existing row showing existing totals of quantities of each item.
2 1 0 1 0 - This is a new row of items subtracted.
3 4 8 2 15 - This is the new row showing the new totals of quantities of each item.
4 3 0 5 4 - This is a new row of items added.
5 7 8 7 19 - This is the new row showing the new totals of quantities of each item.

Rows ID 2 and 4 are manually entered, but I would like to be able to require Access 2007 to calculate the totals shown in rows 3 and 5.

Can that be achieved?

i.e. Can I add (or subtract) a new row from the previous row and place the result in another new row automatically?

If so, how?

Thanks

David

 

[Rabbie]

This link may give you some insight on how to tackle the problem

 

[wdrspens]

Thank you. It gives me food for thought and further investigation.
Regards
David

 

[CEH]

Do a search for DB's for inventory.... Sounds like what you have here.

 

[wdrspens]

Thanks, Curtis. It is similar to an inventory and your idea also gives me food for thought.
David