Posted by Terence on 08/18/05 07:55

We use a combination of timeout and user who has locked the record in a
form e.g.

User A opens the form. A record id is stored in the page and the db
record has 3 cols -> is_locked (y/n), locked_by (user_id) & locked_time
(datetime)

B then opens the form.
If the record is locked & more then 5 minutes has passed then B's ID
will then be updated into the table and a new locked_time set.

If it's locked and within the time an error message pops up saying
"Record locked by XYZ for another 3 minutes".

If user A comes back in 10 minutes and submits, the sys checks if his
user id is in the "locked_by" col, and then alerts him that his 5
minutes were up and he needs to refresh.

It's never let us down. If you can improve on it let me know :)

Bret Walker wrote:
> Hello-
>
> I'm developing a web-based system whereby users can edit documents and
> then e-mail the documents to selected recipients.
>
> The "documents" are comprised of the data from several MySQL fields.
>
> I want to make sure that two people don't edit a document at the same time.
>
> My users log in via a script that starts a session.
>
> My initial idea was to have a field to denote file access (1 for "in
> use" 0 for available). The problem with this would be if a user
> navigates to a different page or closes the browser window without
> clicking a "save" or "close" button (which would execute a query to set
> the in_use field to 0).
>
> I'm sure others have dealt with the issue of exclusive access to a MySQL
> resource. I've looked into InnoDB transactional support, but that
> doesn't seem to be what I need, since I'm not overly concerned about
> simultaneously access, just simultaneous editing.
>
> How can I ensure the "document" isn't accessed by two people at the same
> time?
>
> Thanks,
> Bret

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