JWColby
jwcolby at colbyconsulting.com
Fri May 4 11:21:25 CDT 2007
C'mon Charlotte, give me something to poke at. ;-) John W. Colby Colby Consulting www.ColbyConsulting.com -----Original Message----- From: accessd-bounces at databaseadvisors.com [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Charlotte Foust Sent: Friday, May 04, 2007 12:14 PM To: Access Developers discussion and problem solving Subject: Re: [AccessD] When to Use a Junction Table The first rule is "Never believe 'never'". When I hear that word, I automatically assume the change will come sooner, not later. I always normalize this kind of data because it makes it so much easier in the long run...or in the short run if the change comes next week. Let's see, I've heard things like: The account code will never be longer than 8 characters (oops, we changed accounting programs...) We'll never need more than two addresses We'll never need a <fill in the blank> field - we don't capture that information A company will never have more than one contact name A contact will never have more than one email address/phone number/mailing address/street address ... Get the picture? Charlotte Foust -----Original Message----- From: accessd-bounces at databaseadvisors.com [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Elizabeth.J.Doering at wellsfargo.com Sent: Friday, May 04, 2007 7:36 AM To: accessd at databaseadvisors.com Subject: [AccessD] When to Use a Junction Table Hullo Gurus! I'm trying to decide if I am just lazy since it is Friday. Or if this will come around later to haunt me ..... A bank has a call center for handling people who have questions about their credit cards. Call center workers are divided into groups which have slightly different permissions to give certain kinds of credits. The list of groups is very limited--three groups--and the list of credits is pretty limited as well, perhaps 35. The right way to structure tables so that I can look up to see if a certain user in a certain group has a certain permission is absolutely to have a table Credit and another table Group and a junction table Permission with foreign keys CreditID and GroupID (and a primary key of PermissionID.) The lazy way causes me less grief in the short term: I make one table Credit, with three additional true/false fields for the three Groups. This way, I spent less time today documenting tables and sprocs to make officialdom happy. In the long run however, I have more grief if a new Group is added. Of course, everyone swears there will never be a new Group. In all of your combined experience, does "there will never be a new Group" mean, "there will be a new Group next week" or "there will be a new Group, but not for years and years" ? How would you structure this? Thanks, Liz Liz Doering elizabeth.j.doering at wellsfargo.com 612.667.2447 "This message may contain confidential and/or privileged information. If you are not the addressee or authorized to receive this for the addressee, you must not use, copy, disclose, or take any action based on this message or any information herein. If you have received this message in error, please advise the sender immediately by reply e-mail and delete this message. Thank you for your cooperation" -- AccessD mailing list AccessD at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/accessd Website: http://www.databaseadvisors.com -- AccessD mailing list AccessD at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/accessd Website: http://www.databaseadvisors.com