Re: mySQL query question
| From: | Bastien Koert | Date: | Fri, 14 Nov 2008 15:24:48 +0000 |
| Subject: | Re: mySQL query question | ||
| References: | 1 | Groups: | php.general |
| Request: | Send a blank email to php-general+get-283300@lists.php.net to get a copy of this message | ||
On Fri, Nov 14, 2008 at 9:58 AM, <ceo@l-i-e.com> wrote:
>
> > okay I want to pull an integer from a database called confirm_number,
> > add 1 and repost it back to the database
>
> No, you don't want to do that.
> :-)
>
> You are introducing a race condition between TWO users who hit the same
> page at the same time.
>
> They each get, say, 42, and they each put back 43, but one of them should
> have been 44.
>
> What you WANT to do is this:
> update contacts set confirm_number = confirm_number + 1 order by contact
> desc limit 1
>
>
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>
yep, our current app, designed by 'brighter minds' than mine, refused to
make these auto numbers and now we have problems caused by the race
condition.
--
Bastien
Cat, the other other white meat