hello,

I have several HTML forms on a remotely-hosted website that are
processed by PHP scripts. The form data is entered into a MySQL
database. Occassionally, after submitting a form I get the following
message:

"Warning: Page has Expired The page you requested was created using
information you submitted in a form. This page is no longer available.
As a security precaution, Internet Explorer does not automatically
resubmit your information for you.

To resubmit your information and view this Web page, click the Refresh
button. "

If the Refresh button is clicked, then the form is resubmitted.
Without getting into the details of the application, such duplicate
form submissions are very problematic.

Is there any way, perhaps using Javascript, PHP, or other technologies
(MySQL?) that can prevent the form from being resubmitted upon
refresh? E.g. flushing out the HTTP_POST_VARS somehow upon page
refresh? Or preventing the message from appearing (maybe redirecting
the user to another page?)

Thanks,
Darren

The typical way to solve this problem is to have PHP generate a unique
identifier as a hidden field in the form.  Then add a field to the
database to hold the unique identifier.

Before the new entry is added to the database the PHP script checks to
make sure that the unique identifier is not already in the database.
If it is already in the database then you either discard the new
details or overwrite the existing database entry depending on what you
want to do.

Check out the following link which details about how to generate a
unique identifier.
http://www.zend.com/manual/function.uniqid.php