Arthur Fuller
artful at rogers.com
Tue Aug 19 14:03:06 CDT 2003
Thanks! It'll take me some time to sort out what you said with examples, but you've given me good leads and thanks for them. -----Original Message----- From: dba-sqlserver-bounces at databaseadvisors.com [mailto:dba-sqlserver-bounces at databaseadvisors.com]On Behalf Of Djabarov, Robert Sent: Tuesday, August 19, 2003 12:53 PM To: dba-sqlserver at databaseadvisors.com Subject: RE: [dba-SQLServer]Roles and Rules etc. Having rules and CHECK constraints may be an overkill and somewhat cumbursome to maintain. I would stick to one or the other. There's still a benefit of using rules because a rule can be bound to columns in different tables, while CHECK constraint will have to be re-created for each table and can be bound to multiple columns within a table. Another advantage is that you can bind a rule to a user-defined datatype which will be implicitly used wherever you use this datatype. Mind you though that it may be very hard to debug! Disadvantages of using rules are: (1) each column/datatype can have only one rule bound to it at a time; (2) If a rule is bound to more than one column (and even worse - more than 1 datatype) even existence of documentation on that would not ease the potential maintenance nightmare. I have to work with a lot of code that came all the way from 4.2a on OS/2, so I see rules all over the place and have internal usage diagrams and matrices that define each rule and its usage. Nightmare? Hell yeah! But some view it as job security :) What's BCNF? -----Original Message----- From: Arthur Fuller [mailto:artful at rogers.com] Sent: Tuesday, August 19, 2003 11:24 AM To: dba-sqlserver at databaseadvisors.com Subject: RE: [dba-SQLServer]Roles and Rules etc. 1. So does that mean, forget about them and use check constraints exclusively? 2. Can a check constraint apply to multiple columns? Or is that by definition a failure to go to BCNF? A. -----Original Message----- From: dba-sqlserver-bounces at databaseadvisors.com [mailto:dba-sqlserver-bounces at databaseadvisors.com]On Behalf Of Djabarov, Robert Sent: Tuesday, August 19, 2003 11:36 AM To: dba-sqlserver at databaseadvisors.com Subject: RE: [dba-SQLServer]Roles and Rules etc. Rule doesn't have anything to do with roles and permissions. It's similar however to CHECK constraint. BOL: "Rules, a backward compatibility feature, perform some of the same functions as check constraints. CHECK constraints, created using the CHECK keyword of ALTER or CREATE TABLE, are the preferred, standard way to restrict the values in a column (multiple constraints can be defined on one or multiple columns)." --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.510 / Virus Database: 307 - Release Date: 8/14/2003 _______________________________________________ dba-SQLServer mailing list dba-SQLServer at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/dba-sqlserver http://www.databaseadvisors.com _______________________________________________ dba-SQLServer mailing list dba-SQLServer at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/dba-sqlserver http://www.databaseadvisors.com --- Incoming mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.510 / Virus Database: 307 - Release Date: 8/14/2003 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.510 / Virus Database: 307 - Release Date: 8/14/2003