OK I see the advantages of a numerical ID for both my Vins table and my Orders tables.

So is it like this then?

tblVins

-------

VinID -- numeric -- Primary Key

Vin -- 17...

I think you're getting lost in the verbiage/usage of PO Number

Our customer issues a PO Number (their purchase order number) to the MFG

One unique PO Number with X number...

This concerns me:

You heard only part of the story. SQL has an IDENTITY property. This works in the same manner as an auto increment in Access.

You would use this...

Well each client has their own PO number scheme, and they submit to us their order. Those Order Numbers come attached to each VIN from each manufacturer, we have 10+.

We...

Thanks Michael for the advice, I will do some reading up on the site you advised.

it is 1 to Many...

PO is issued for let's say 20 vehicles.

20 Vins fill that Order

Each Vin row has the POnum field

So using two non-numeric fields as keys won't affect performance given the number of records that I'm talking about?

Also what about the field type Char, VarChar ??

(I just tossed in...