Answer 1

You could use some random password generator to fill a hidden input box on your form then just con cat with some starting string and an ending digit which is incremented with a counter OR better still the ID location of a database to keep better track

Mytracking +(random generated password) + database id

If the order placed was the first saved in the database then you would have "My tracking(password)(database ID no. 1)"

Plus tracking number will always stay with customer.

This can be big and you would need to give overwritten abilities for new orders, expired dates so old orders are overwritten and so on

The integers would have to be pharsed to string first if im not mistaken