Ok, I have to ask. What kind of application are you using where using pseudo random numbers for customer ids isn't good enough? I'm already amazed that sequential numbers can't be used, but not even PRNs?

Well, even if you have 900,001 customers, you have a problem, unless ids are allowed to have leading 0s. Of course, even if you have 100,000 customers, using 6 digits for the id in combination with being truely random and unique doesn't make much sense.

Abigail