Your friend is right. A primary key should have no other meaning than being that and should never be seen by the user. I would go further in recommanding that you add a primary key in your detail table (inv_detail_pk).

>what's the right table structures for one-to-many forms?
>
>eg. for invoicing, I use:
>
>invoice.dbf
>---------------
>inv_no
>inv_date
>cust_id
>
>inv_detail.dbf
>------------------
>inv_no -> foreign key of invoice.inv_no
>stock_id
>qty
>price
>
>while my friend insists the right way is:
>
>invoice.dbf
>---------------
>inv_pk
>inv_no
>inv_date
>cust_id
>
>inv_detail.dbf
>------------------
>inv_fk -> foreign key of invoice.inv_pk
>stock_id
>qty
>price
>
>in his opinion, the key shoud be meaningless, not represent anything.
>
>while my way (using invoice number) will cause lots of problem in the future, espesially with SQL databases.