Charlotte Foust
cfoust at infostatsystems.com
Wed Jul 25 11:41:06 CDT 2007
It's usually the approach I use for M to M tables, and the only drawback I can think of is that if you needed a foreign key back to this table, you'd have to use both/all PK fields, not just a single autonumber. Charlotte Foust -----Original Message----- From: accessd-bounces at databaseadvisors.com [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of John Bartow Sent: Wednesday, July 25, 2007 8:31 AM To: 'Access Developers discussion and problem solving' Subject: Re: [AccessD] Primary Key Best Practices Jim, This is something I haven't seen before and is in my early morning mind, quite brilliant! Are there any drawbacks to doing this? I can't imagine it would be much of a difference (size or performance wise) in any of my applications / databases but it is certainly something worth considering implementing in the future. Always open to technical improvements... -----Original Message----- From: accessd-bounces at databaseadvisors.com [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Jim Dettman True, but in the case of a M to M table your just introducing another column and a index that really is not needed. It seems silly to me to have something like: tblLinking LinkID - Autonumber - PK BookID - Long - CK1A AuthorID - Long - CK1B Instead of tblLinking BookID - Long - PK1A AuthorID - Long - PK1B just for the sake of having an auto number in there. The BookID and AuthorID already form a unique pair and they typically would not be used as a foreign key in another table. -- AccessD mailing list AccessD at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/accessd Website: http://www.databaseadvisors.com