Prevent user to use back button with warning or disable any insert

Question

I have a form in page1.php which directs to page2.php from where the data from the form in page1.php is inserted into database. after

Answer 1

You should not display your message on page2.php.

Instead :

• page2.php should deal with the data
• when the data has been saved, page2.php should redirect to confirmation.php
• And it's only confirmation.php which would display the message.

For more informations, take a look at the Post/Redirect/Get pattern.

Edit after the comment : but note that, in any case, you will never be able to prevent the user from re-submitting a form, if he really wants to...

The only solution you'll have is, when a form is submitted, to check in your database if the currently submitted data already exists -- and if it does, refuse to insert it again.

Of course, if the suer changes even a single letter in his input, it won't be the same data anymore...