Immediate Updates on Table

I am using VB with Access in Windows NT.
How to Update Records Immediately?

I am Working with Stock Program When two user make the sales for same item. Stock goes negative.
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vikiingConnect With a Mentor Commented:
If two different stations address the same product, both will think "There are 50 units of this", then one will sell 40, and the other will sell 30, leaving, in both cases the wrong value for the remaining stock.

To handle that situation, you need a semaphore which indicates when a certain record is available to use. If semaphore indicates a certain resource (in this case, the item record) is locked, then you must wait until the record is unlocked (the other application fress the record once it was updated).

Some data base managing systems handle semaphores automatically (which are intended for multi-modifying-users access); some others, simply not, and therefore, you must develope the concurrency control.

Issue an SQL update command.

Send a SQL statement such as:

    set stock_level = stock_level -100
  where stock_id = 9987

Good luck.
ackid32Author Commented:
im using Access as backend and how can i use semaphores
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ackid32Author Commented:
Comment accepted as answer
ackid32Author Commented:
pls reply me
Semaphores are special indicators which handle the way a multiple-users transaction is carried over. As a rule, the own DBMS handles them, this is, the data base management system is who "serializes" concurrent transactions to execute one at a time, as if they weren't performed simultaneously.

But if your DBMS doesn't use them, then you must implement the semaphore scheme by yourself. Read some data base literature.

Thanks x the points.
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