I have developed a with Php and Mysql. As more people are working on it simultaneously, there is the danger that two users have the same form on the screen, and one user changes fields, while the other is then working on old information.
When this latter submits, he will destroy the changes that the first user made. Is there a neat way to prevent this? Blocking certain pages, making a warning? How does that work in PHP and/or Mysql?