Multiple users attempting to purchase item at once, Locking row?

Question

Say I was to offer an item to multiple users, up to a maximum of say 10 purchases can be made by any user until the item is 'deactivated'. The items are taken from the mainitems table and filtered to the specific users.

For each purchase a count is incremented in the items row to indicate the amount of purchases made. How can I control say 11 users all trying to purchase this item @ once? Is the best way to acheive this by simply locking that row until the purchase is completed and then compared? Or is there a way I can do this without having to constantly remove the results from other users and then reactivating them?

check this http://stackoverflow.com/questions/6914122/mysql-innodb-transaction-concurrency — Venu, Jun 23 '12 at 10:47
I don't know PHP much, but is there anything in PHP like we have **Synchronization** in Java? — Fahim Parkar, Jun 23 '12 at 11:46
Look into transactions as the answer here suggests, it's the way to go. — Mahn, Jun 23 '12 at 11:47

score 1 · Accepted Answer · edited Jun 23 '12 at 11:44

1

You should use a sql transaction and in php you should use try{} catch(){} statement

try
{
//mysql begin transaction


//the code that does what you said it would do


//mysql commit transaction
}
catch(Exception $ex)
{
//mysql rollback

/return false
}

In this way, I dont think it would be the case that two users ask for the item in the same time the transactions are treated FIFO.

edited Jun 23 '12 at 11:44

Fahim Parkar

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answered Jun 23 '12 at 10:50

iMoldovean.com

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Multiple users attempting to purchase item at once, Locking row?

1 Answers1