How to change the PDF file

I have created PDF file by using php script and FPDF lib. It works fine, i have created two files named index.php and create_result.php in the file create_result.php i have written the php script for pdf file. what i want is that if i changed any program in this file there is no change in pdf file. my confusio开发者_开发知识库n is how to change the pdf file ,

ex:(result.pdf).

In the result.pdf file i have made a registraion form , if i want to change any thing in this result.pdf in the sense what should i do for a change?

Two things:

1. Does the Server have the permission to overwrite the PDF
2. Do you write Data from you login-Script into the PDF? If so, you have serious problems with multithreading, becaus one user can change the PDF for another user. You have to write a temporal PDF-File per user, with a unique filename.