we have four tables in ms access db as mantioned under with some releted field name.

1. cost_itemcost (Item Costing)
item_id (unique key)
cutting_cost - in this field we are storing equation like
(0.00624*finish_wt) + (nickle+cromium) + (finish_wt-cut_wt)
forge_cost - same as above

2. cost_matprise (Material Pricing)
mat_id (unique key)
mat_name
nickle
cromium

3. cost_itemwt (Item Weight)
item_id (Unique key)
finish_wt
cut_wt
forge_wt

4. m_item (Item Master)
item_id (unique key)
item_desc
mat_id (Foreign Key)

first we are inserting data in cost_matprise for creating material name then the same mat_name we are using in item master. after that for this item we are defining item weight in cost_itemwt table. after done above process we are defineing item costing in cost_itemcost table through equations.

Now our problem is.....
If we will upadate cost_matprise or cost_itemwt or both tables then how to update the cost_itemcost automaticlaly thru vb or ms access.