>> I'll give you the exact case where I'm worried:
>>
>> We have a table of customers, and each customer can have multiple
>> memberships (which are stored in the memberships table). We want our
>> deleteMembership(int membershipID) method to remove the membership, then
>> check to see if there are no more memberships left for the corresponding
>> customer, and if there are none, delete the corresponding customer as
>> well.
>>
>
> Hum.. yeah, I can see a race condition there. but even with table
> locking I can see it. Not sure how your stuff works, but I'm thinking
> website:
>
> user1 goes to customer page, clicks on "add membership" and starts
> filling out info.
>
> user2 goes to customer page, clicks on "delete membership" of the last
> member ship, which blows away the membership, then the customer.
>
> user1 clicks save.
>
> Wouldnt matter for user2 if you locked the table or not, right?
>
> -Andy
In the case described above, our code would throw an exception saying
"Customer no longer exists", prompting the user to create a fresh
customer - So I'm not worried about this (Although it may be
inconvenient for the user, I don't think much can be done in this case).
Please let me know if I've missed something here.
I'm more worried about the following situation (Where a bad interleaving
sequence happens):
user1 goes to customer page, clicks on "delete membership" of the last
member ship, which blows away the membership,
user2 goes to customer page, clicks on "add membership" and starts
filling out info.
user1 then blows away the customer.
However I guess that if the relations are set up properly in the
database, an exception could be thrown to say that there are
corresponding memberships still exist...