How to change "id" in url

If my website is : web.com/index.php/z_tbl_user/update/119.
What i afraid is then visitor could change it to be this : web.com/index.php/z_tbl_user/update/120.
To prevent this i want to change so the visitor see is something like this  :   web.com/index.php/z_tbl_user/update/whscbscbxncbxn922.
So how to change the 119 to be some alphabet that is random?Are there any library or function? I google but i still confuse how to implement
Thanks for help.

I thing you just have to wrap the form in an if statement, for example(that's how I have it right now):



and as a guy already said, if you have a function to ban users who are just changing their id to see if they can mess with somebody else .... then do it.... make sure to put the form_submit and form_close before the else stament.

I do Front-End development most of the time