How to make a random number database?

hello, I'm trying to figure out how to make a database. I would like people to be able to sign up, then they get a 10 digit code that's attached to their name. Afterwords I would like to be able to add people to it and have the code automatically generated but never dublicated. Then I want to make it frozen so it won't change once it's set. It has to be for long term storage. It's a program I'm writing where people buy a ticket" and then that ticket is worth somthing in 10 years if they have their code and the name attached to it. The basic idea is you buy a ticket and all money goes in to a pool then combined interest is divided after ten years. I'm trying to think of a way to close all loop holes to stop impersonation or fraud, but still make it transferable to next of kin just in case their is death....I know it sounds far fetched but it's a mental excresize thing. Any suggestions?