artful at rogers.com
artful at rogers.com
Wed Dec 27 23:43:04 CST 2006
Joe and I have corresponded occasionally for several years. I deeply respect his knowledge and depth but here and there I take issue with him. This is one case in point. Suppose that I create a table Sales with an Autonumber (or Identity if in SQL). What is wrong with exposing this value to the user? Of course, the front end should prevent editing of this value, but that is another question. I do not see the problem with exposing the ANPK to the user. It becomes the SalesID and the printout exposes it and the customer uses this number when calling to question about the Sale. What is wrong with that? Maybe I'm missing something here, but I've been doing it this way for 20+ years and cannot recall a problem with it. I don't care about sequences without gaps. I don't care if you attempt to insert then cancel 100 times in a row. Not my issue. But should you insert and save and then print it (to PDF for email or whatever), then the customer has a unique number to refer to this sale. I don't understand why we should add a new number. What is wrong with the PK? Granted, the systems should not allow this number to be edited, but aside from that, what is the problem? Arthur ----- Original Message ---- From: MartyConnelly <martyconnelly at shaw.ca> To: Access Developers discussion and problem solving <accessd at databaseadvisors.com> Sent: Wednesday, December 27, 2006 5:12:19 PM Subject: [AccessD] Surrogates vs Natural A Bit More on Defining Keys Joe Celko spouts off on one of the basics of database design. This statement should set it off. " This means that a surrogate ought to act like an index; created by the user," managed by the system and NEVER seen by a user. That means never used in queries, DRI or anything else that a user does. Auto-numbering is an exposed physical locator and not a surrogate." http://www.tdan.com/i038ht04.htm -- Marty Connelly Victoria, B.C. Canada -- AccessD mailing list AccessD at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/accessd Website: http://www.databaseadvisors.com