Re: Help with inventory control

Fernando Grijalba <fgrijalba(at)gmail(dot)com> writes:

> Thank you for your response.
>
> I want to avoid the following situation.
>
> User1 starts order and takes the last two units. User2 starts order 1
> minute after and checks inventory. He sees 2 units left and adds them to
> the his order. User1 commits his order. Now User2 cannot finish his
> order because the products are not available anymore.
>
> This is the problem I want to avoid. Therefore if User1 takes the product
> but does not finish the order I want the inventory to still show that the
> product is sold out to other users.
>
> Any suggestions on how to implemnt that?

I think just using SELECT FOR UPDATE should solve this problem--it
will lock the row and SELECT FOR UPDATE in the second transaction
won't return until the first transaction commits.

-Doug