How to create an 8 digit unique and random number for each posting in php

[kee2ka4]

Hey peeps,

 

I wanted to create a Random and a Unique Number of 8 digits that will represent each unique advert posted by users. I have an advert_id in the database that is the primary key but I do not want to use that on the site for security reasons. So each advert_id will have a unique 8 digit number which will be stored in the table under column name Ad_num. Could anyone guide me how to do this.

 

The 8 digit number has to be unique and random and no fields in the database can have the same number.

 

Thanks,

Zub

[php.ajax.coder]

You could use a timestamp with a random number added to the end e.g.

 

<?Php
  echo time() + rand(0,9);
?>

[kee2ka4]

Thanks for your reply, The only problem with timestamp value is that it gives 10 digits but I guess I can do with that. I think if I also add the advert_id to the value it will be certain that it will give me a unique number. Can the time() function ever give the same timestamp value?

[AndyB]

Can the time() function ever give the same timestamp value?

 

Only if time stands still.

[thebadbad]

Can the time() function ever give the same timestamp value?

 

Only if time stands still.

 

And if run more than once within the same second.

[thebadbad]

Check out uniqid().

[CroNiX]

And if run more than once within the same second.

then use microtime();

 

[Conjurer]

A random number is not unique. Roll the dice, each roll is a random number.  But you will often get the same number repeating.  That is part of randomness.

 

You want to create a unique number.  Start with a number and increment it.

[CroNiX]

or, create a random number, check db to see if it exists, if not insert it