I have codes to identify the user when an user try to modify the
database using id.This is useful for preventing others to modify a
user's data.But after a registered user login,he can still modify the
data that has been saved to the database sometime ago by inputting the
url containing id in the browser.How do i prevent displaying id in the
brower so that user can not see the id and modify the database by
inputting url in the browser?
Mmmm. The better solution to your problem is called authentication.