How to generate unique numbers/IDs without duplicates?

Question

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PHP: How to generate a random, unique, alphanumeric string?

I wish to generate Product Keys or Licenses using PHP. Is there a function that allow me to do generate unique numbers/IDs but at the same time make sure that there won't be a chance for duplicate?

Thank you.

score 2 · Accepted Answer · answered Jun 30 '11 at 05:41

2

You could use php's uniqid function to generate id's:

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

or leave that responsibility to the database engine, which will generate auto-incremented id values.

answered Jun 30 '11 at 05:41

Headshota

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score 1 · Answer 2 · answered Jun 30 '11 at 05:39

1

Use a uniqid

answered Jun 30 '11 at 05:39

Gabi Purcaru

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score 0 · Answer 3 · edited Nov 14 '12 at 15:04

0

You can use md5(timestamp), its always unique

edited Nov 14 '12 at 15:04

Mike Mackintosh

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answered Jun 30 '11 at 05:39

Sandeep Manne

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unless 2 calls are made at the exact same time! – Ben Rowe Jun 30 '11 at 05:43
exactly as @BenRowe mentioned: If you generate multiple keys during one PHP call this will definitely end with duplicates – Philipp Jul 05 '16 at 18:01

How to generate unique numbers/IDs without duplicates?

3 Answers3