Generate random unique serials

Question

I want to build a token number generator. In each call, a random and unique 8-digit number should be returned. I am using PHP and MySQL. In MySQL I'll have a table where I will insert the new serial, each time it will be generated.

How can I generate new numbers in each call?

Tokens will be used from end-users to activate software (and will expire, e.g. after 1 week). So, I need tokens to be unique and not sequential. This describes better my needs. Token format will be just numbers, so that it can be easily spelled and typed.

Even if tokens expire, I do not want to generate an already generated token at a later time.

Thank you

is this valid 11223344? or all numbers are unique 12345678? — John Woo
– John Woo, Commented Jan 15, 2013 at 0:08
@ROYFinley, although that would generate unique id's they could hardly be described as random — Crisp
– Crisp, Commented Jan 15, 2013 at 0:08
Technically, the phrase "serial number" means a number that increases as a series. ie not random. — paddy
– paddy, Commented Jan 15, 2013 at 0:13
"Random", "unique" and "an unknown number of" (implied by the question) in the same sentence does not make sense. In all likelihood you want unpredictable and unique. — Jon
– Jon, Commented Jan 15, 2013 at 1:05

jacobgelman · Accepted Answer · 2013-01-15 00:59:41Z

Ok, so this code does not put the serial number into a database but it will return a serial number 8 digits long. If you want just numbers change the allowed characters variable to just numbers.

<?php function generate_serial_number() { $Allowed_Charaters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890'; return substr(str_shuffle($Allowed_Charaters), 0, 8); } ?>

Thank you for the generator, but this does not fulfills the number-unique requirement. Of course, I can insert it in the db until I get no error (due to the unique definition of the relative column).

napolux · Accepted Answer · 2013-01-15 10:21:52Z

0

I usually use http://php.net/manual/en/function.uniqid.php with the more_entropy parameter to true.

answered Jan 15, 2013 at 10:21

napolux

16.2k9 gold badges55 silver badges72 bronze badges

2 Comments

Tsiftis Karampouzouklis Over a year ago

That sounds good, but how can we get rid of the alphas in there?

napolux Over a year ago

Strip them. Use preg_replace(). But beware, you can have collisions.

Collectives™ on Stack Overflow

Generate random unique serials

2 Answers 2

1 Comment

2 Comments

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

2 Comments

Related