Create unique GUIDs - need help

I want to create unique IDs for my members which will be 6 chars long and will be prefixed by alphabets.

Example: ft8795

Does anyone know which is the better way to do this?

Thank you Jono for replying.

Actually I have little knowledge in this part.

I learned that using Server.CreateObject("Scriptlet.TypeLib") or stored procedures I can create GUIDs. I found couple of other functions that says that generate GUIDs. But my problem is I never worked with GUIDs.

Actually I need unique IDs for couple of things. Currently I am working on a system that requires unique order ids, receipt ids, event ids and member ids. My problem is I cannot just generate integer autonumbers and assign them as IDs - like the author_ID in WWF. I need strings prefixed by alphabets. And I do not know which way to go.

Another thing I am considering is a GUID string is not short in length. If a shorter length unique IDs can be created, say 6 to 10 chars long, it will be better - or is it impossible? But I cannot just depend on the system timer and create simple IDs because I cannot take the risk to generate duplicate values.

It is new to me and I am confused what to follow.

It is not for WWF and I plan to script the whole application in Access and then port it to MS SQL.

Ow, missed again, sorry.

I guess a sequential unique ID could be a security risk because anyone can guess what's after or before the sequence.

Jono wrote: Either way, I suspect you'd need to generate an ID and then query the database to make sure it's not in use.

But this way, there might be loops and the database will be huge after 1 year of use. The whole thing is a business application. So, querying the database can be a performance issue. Note, I have to generate unique Ids not only for my members but there are other Ids also.

Jono, thanks for your reply.

Jono wrote: ....if someone, for example, want's to view an invoice, it should either be their invoice

Right Jono. But it's not about viewing an invoice or order, actually there are other issues. I do not want someone guess an order number or a support ticket number or a reference number. Because some numbers(like orders and references) will be used in some hard copied docs of the company. And if someone can guess those numbers, he might be able to guess some information even have access to some information phisically or ver the phone that the company might not want to expose. And if it happens somehow, ultimately the headache will come on to me. Look we all know business men are not that much IT aware. So, it is pretty possible getting more information from a normal staff by only providing an order number and the reference number to that order. So I need those as non sequential.

Jono wrote: GUID's are special type of ID's and, as you've guessed, not exactly what you're after

So, are you trying to say that I can generate unique IDs without creating a GUID? How? Consider there will be performance issues.

Or, if it is impossible to generate unique IDs, is there a way to shorten the lenghth of a GUID? like, converting the GUID or some part of it to another value?

Your suggestion do helps me undertand where i am. Thank you very much for helping me through this and I look forward to get some more till I get a solution from you!