How to create a unique order number

Algorithmically speaking, how could I generate a unique, human readable, reasonably lengthed - order number for SQL Server column. The only requirement is that it references the Customer Number and can be easily repeated over the phone.

Something like:

• Customer Number - XXXXXXXX - XXXXXXXX

RT65-XXXXXXXX-XXXXXXXX

How would I generate the XXXXXXXX? (Use random alpha-numeric data and then checkin开发者_如何学编程g to see if it was in fact a duplicate?)

and

What are the best methods/considerations when generating these types of numbers?

How have you done this in your application?

Use an identity column and pad with zeros.

Alter the start and increment values to taste.

Optionally, add a CRC check digit.

Check out these posts, nearly the exact same question. Real good data in both (I've used them before):

A good algorithm for generating an order number

What is the best format for a customer number, order number?

This is silly but fairly straight forward, How about yyyymmddhhmmss

and use it with

RT65-XXXXXXXX-XXXXXXXX

in php you can do like the following:

<?php 
$stamp = strtotime("now");
$orderid = 'RT65-'.$stamp.'-'.$REMOTE_ADDR; 
$orderid = str_replace(".", "", $orderid); 
echo($orderid); 
?>