There are many ways to handle this.
You might get the current quantity on hand, and compare to orderqty
update inventory set qtyonhand=qtyonhand - orderqty where
itemno='myitemno' and qtyonhand=myqtyonhand
If the query fails, repeat until qtyonhand < orderqty or update
succeeds.
Every hour or so, go through your shopping carts, and
post ordered qty back into inventory for all abandoned carts.
Daniel B I wrote:
>
> Please, any idea how to manage concurent requests,
> for example like in a shopping cart?
>
> Scenario:
>
> 1. I have a counter A (a field in a database row), set to 1, so A=1
>
> 2. A client wants 1 unit from A , it checks and it's OK,
> there is available.
>
> 3. Another client wants 1 unit from A, it checks, and it's OK,
> because first client did not subtracted yet 1 unit from A
>
> 4. The first client decreases A, so A=0
>
> 5. The scond client decreases A, so A=?... some garbage...
>
> Any idea how to fix this transaction problem? If A is locked by the
> first client in order to fix this problem, there is another question (the
> really one!):
>
> If the program terminates unexpectedly, what about A?
> It remains locked forever, and the second client cannot use it
> anymore ?
>
> thanx!
> any idea really apreciated!
>
> Daniel BI
>
> ---------------------------------------------------------------------
> Before posting, please check:
> http://www.mysql.com/manual.php (the manual)
> http://lists.mysql.com/ (the list archive)
>
> To request this thread, e-mail <[EMAIL PROTECTED]>
> To unsubscribe, e-mail
><[EMAIL PROTECTED]>
> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
---------------------------------------------------------------------
Before posting, please check:
http://www.mysql.com/manual.php (the manual)
http://lists.mysql.com/ (the list archive)
To request this thread, e-mail <[EMAIL PROTECTED]>
To unsubscribe, e-mail <[EMAIL PROTECTED]>
Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
