This is another good idea. When reloading the page, have the script generate
that unique ID, store it in a separate table AND  put it in a hidden input.
When the user submits, the database checks to see if the unique ID is in the
database, and if so, the ID is deleted from the database, and the order is
processed. On subsequent clicks, the unique ID would not be found in that
database table so the query would fail with a message ("You have clicked
more than once") or something like that, and the person could check the
status of an order identified by that unique ID.

- Jonathan

-----Original Message-----
From: Aron Pilhofer [mailto:[EMAIL PROTECTED]]
Sent: Monday, March 04, 2002 9:51 AM
Subject: Re: [PHP-DB] Tutorial?

The easiest and best solution is to redirect to a new page after the submit.
But I have had cases where it was necessary to have the submit code and the
form on the same page.

I agree totally with jonathan that a server-side solution is the way to go.
To solve the problem (avoid clicking twice and/or reloading the page) I used
a hidden field that generated a unique ID based, and then placed that into a
field that only accepts unique values. If the user reloads, the query
fails - trap that error and you're golden.

"Jonathan Hilgeman" <[EMAIL PROTECTED]> wrote in message
> Hi Jennifer,
> I'm guessing the purpose of this would be to keep people from
> double-clicking and submitted information twice, possibly making an
> application deduct payment twice or something important similar in nature.
> The best way I've found of accomplishing the goal of keeping people from
> clicking twice has three parts:
> 1) Quickly switching the page. On the next page, have PHP write out about
> 300 spaces and a newline, then call the flush() function to make the
> get sent to the browser. In many cases, this will cause the browser to
> quickly switch to the next page and display a blank page while the data
> processed.
> 2) It's still remotely possibly to click twice even if you have part 1 in
> place, so this is a more fool-proof method. Store your data in a database
> before processing it - along with a timestamp. When the person clicks the
> submit button twice, the program checks the database to see if there is
> same information with a very close timestamp. If so, update the timestamp
> the database. At this point you can choose 3 paths:
> - Store the data so you can batch-process the data at a later time, once
> are sure that the visitor has left and there will be no more clicks. For
> example, have a program that runs every 5 minutes (via cron), then have
> program check for data/orders that are at least 5 minutes old, and process
> them. That means that the timestamp hasn't been updated by extra clicks in
> minutes (and you could still have notified the visitor that their order or
> data request is now in line to be processed).
> - Process the data immediately. If you need to process an order
> and give back results, use the above method, but modify it a bit. Instead
> just displaying notification that their order is in line to be processed,
> you can submit to another PHP program which sleeps for about 3-4 seconds,
> then checks the database until there are no clicks for at least 4 seconds,
> and THEN processes the data, and returns a value to the screen in like 4-5
> seconds. Both of these methods have similar goals, though - Receive data
> timestamp it, Wait $Time, Check for timestamp updates, Process when
> timestamp is $Time old.
> 3) Have a very visible notice that people should not click multiple times,
> or else undesirable results may occur, and we want "your" request/order to
> be perfect. Emphasize the request to click only once and to be patient,
> if something goes wrong, here's how to contact us.
> - Jonathan
> -----Original Message-----
> From: Jennifer Downey [mailto:[EMAIL PROTECTED]]
> Sent: Saturday, March 02, 2002 10:18 PM
> Subject: [PHP-DB] Tutorial?
> Hi all,
> Can anyone point me to a good tutorial on how to disable a submit button
> once clicked?
> preferably in php.
> Thanks
> Jennifer Downey
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