Martin,

>Of course one have to modify some code, but if you are using surrogates, you just need to change the places where the complete invoice ID is used, and you don´t have to do ANY change to the related tables and their management.

Changing the related tables won't be the biggest a problem IMO. Broken views and program lines are. They occur in both using surrogate and intelligent keys.

>>You've pointed out a significant advantage of surrogate keys in most (R)DBMSs (some use domains which makes it possible to address all related fields in one place). Though in the same line there is a significant disadvantage when forced to use surrogate key. See the message to chris in this thread regarding the city issue.
>
>>Here the disadvantage of using surrogate keys might be even more than the advantage in your case.

>I can't understand what you're referring in the last statement. For me the later is a long list of intelligent keys' PROBLEMS.

To what are you refering ? Do you agree that in the "city" case an intelligent key solution (case A) might be the best choice ??

>>We strongly disagree on this point.
>Why?

All these issues can be handled with intelligent keys. I've seen ERP software which almost exclusively uses intelligent keys (Navision). Since it works, and is highly adaptable and I don't see any proof in such a statement.

Walter,