Unique user number

[ericw]

I need to assign a unique number, starting at 1, for a customer invoice number. I need to make as sure as possible it doesn't give two people the same number. As it stands i'm looking at a text file which gets used for assigning a number then incrementing itself and rewriting. Something tells me this may not be the most scalable solution though. Any ideas out there?

[toma42]

What database? With mysql, use an auto_increment field. With postgresql, use a serial field.

[Anon]

see below
$better_token = md5 (uniqid (rand()));

taken from http://www.php.net/manual/en/function.uniqid.php

cheers
nilesh.