Conditional data entry access: intresting

[shanky365]

Hello folks.
I have created a basic inventory system.
now d problem is this: i have created a form for issue of materials and reciept of materials.
1. how can i link the total qty , issued qty and balance qty such that, every time some one issues the same material again, the number gets deducted from balance qty and adds up in issued qty.
for eg
item -total qty--- issued -----balance
bulbs ----10 -------2 ------------8



nw if suppose i again issue 5 bulbs it should not show (its showing in my case)

item ----total qty-- issued------- balance
bulbs ------10 ----------2------------- 8
bulbs -------10 ---------5 -------------5
instead it should show:
item -----total qty------ issued ---------balance
bulbs ---------10 --------7 -----------------3


Alos tell me if i hav 3 tables having total qty , issued and balance qty..... den how can i create sum rule that no can enter issued qty more than balance qty...

u can gv me ideas..or tell me what to search for....

[June7]

Do not try to maintain totals. Purpose of a relational database is to input data then run reports that summarize. Report would sum the receipts, sum the issues, and calculate the difference to show balance. NEVER save a balance. Trying to update running values will drive you nuts.

Need a table to show receipts activity, table to show issues activity. These tables will not relate one-to-one.

Probably require code to check the database and determine if issue amount would exceed available. This can be done behind a form.