Hi,
I am developing POS and inventory system. How could I make sure data accuracy in application during sales and stock deduction in Multiuser mode?
I am using table buffering in my module.
I have the following code in my module. I am not sure that my code can guarantee the accuracy of stock amount.
Since i am using buffering, after I doing UPDATE-SQL (which will minus the current stock balance with sales item count), the stock balance may be changed by other user before I issue TABLEUPDATE().
How to guarantee the balance is accurate?

Thank you

USE salestable AGAIN SHARED IN 1
CURSORSETPRO("buffering", 5)

USE stocktable AGAIN SHARED IN 2
CURSORSETPRO("buffering", 5)

**do watever to search records
UPDATE stocktable SET stockbalance = stockbalance - salesItemCount 
     WHERE stockID = itemID

BEGIN TRANSACTION

** update all table

IF alltableOK
   END TRANSACTION
ELSE
   ROLLBACK
   **REVERT ALL CHANGES
ENDIF