Hi everyone.

I'd like to know if the use of timestamp as a unique id is a good or bad idea.

I am already using an autoincrement, but i need something in addition to that.

Furthermore, i would like to know what would happen if two users on two different computers both submitted a statement at exactly the same time. Would the timestamps be different to each other and therefore unique, or is there a possibility that they might collide?

Thanks for your help.

They could certainly collide as improbable as that is. However, if you are looking for something unique, try the hash of a string appending the IP, a timestamp and a random number.

Hi Kyrnt.

Thanks for the reply.

What exactly is the hash of a string appending the ip?

fambi,

The IP address of your user can be extracted in a PHP script using $_SERVER[REMOTE_ADDR]. It is just a string. microtime() returns the current time. md5() is a common hash function that can be used to convert a string into a 32-bit hexadecimal number.

So here is a function to create the uniqueID you mentioned. I can't test it where I am, but anytime you need a unique identifier, just call this method and the chances are astronomical that you would ever receive two identical uniqueIDs.

PHP Code:


function getUniqueID()
{
    return md5( $_SERVER[REMOTE_ADDR] . microtime() );
} 


Thanks again. I think it will do fine!