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Touché... LOL... It was meant in jest... John Brandt iStudio400.com -----Original Message----- From: DeLong, Eric [mailto:EDeLong@xxxxxxxxxxxxxxx] Sent: Wednesday, November 19, 2003 10:31 AM To: 'RPG programming on the AS400 / iSeries' Subject: RE: the idea of unique primary keys to be a solution that hasoutl ived its usefulness? Except that reorg of that PF would/could change your relative record number. Then any file that refers to record may not retrieve the correct row. The point of an identity column is that its value is unique AND persistent. Once assigned, that single column can describe a unique row, without worrying about the physical organization of the data. Eric DeLong Sally Beauty Company MIS-Project Manager (BSG) 940-898-7863 or ext. 1863 -----Original Message----- From: John Brandt Sr. [mailto:pgmr@xxxxxxxxxxxxxxx] Sent: Wednesday, November 19, 2003 10:12 AM To: 'RPG programming on the AS400 / iSeries' Subject: RE: the idea of unique primary keys to be a solution that hasoutl ived its usefulness? Eric, Given that scenario, the relative record number on a physical (auto number) should be the only key to a file. You can use logicals or SQL to perform all joins. John Brandt iStudio400.com -----Original Message----- From: DeLong, Eric [mailto:EDeLong@xxxxxxxxxxxxxxx] Sent: Wednesday, November 19, 2003 9:53 AM To: 'RPG programming on the AS400 / iSeries' Subject: RE: the idea of unique primary keys to be a solution that hasoutl ived its usefulness? Joep, Yes, I'll agree that compound keys can indeed be considered primary keys. I misspoke; I was thinking of "identity columns" which are commonly used in databases as primary key. The difference between the two designs, imo, is that the widespread use of compound keys makes for inefficient joins between tables. Eric DeLong Sally Beauty Company MIS-Project Manager (BSG) 940-898-7863 or ext. 1863 -----Original Message----- From: Joep Beckeringh [mailto:joep.beckeringh@xxxxxxxxxx] Sent: Wednesday, November 19, 2003 2:47 AM To: RPG programming on the AS400 / iSeries Subject: Re: the idea of unique primary keys to be a solution that hasoutl ived its usefulness? ----- Original Message ----- From: "DeLong, Eric" <EDeLong@xxxxxxxxxxxxxxx> To: "'RPG programming on the AS400 / iSeries'" <rpg400-l@xxxxxxxxxxxx> Sent: Monday, November 17, 2003 10:24 PM Subject: RE: the idea of unique primary keys to be a solution that hasoutl ived its usefulness? > Unique primary keys are not what most of us use on the iSeries. We use > unique compound keys, where the combination of many factors (keys) work > together to define a unique row. Unique primary keys are a single field > that describes a unique row. These are commonly implemented as UUIDs, or > possibly as auto-incrementing value for such things as order number and > whatnot... Who says so? Primary keys can be compound. >From 'A Guide to the SQL Standard' (C.J. Date / Hugh Darwen): In SQL, a candidate key definition takes the form { PRIMARY KEY | UNIQUE } ( column-commalist ). For a given base table, at most one candidate key definition can specify PRIMARY KEY. Joep Beckeringh _______________________________________________ This is the RPG programming on the AS400 / iSeries (RPG400-L) mailing list To post a message email: RPG400-L@xxxxxxxxxxxx To subscribe, unsubscribe, or change list options, visit: http://lists.midrange.com/mailman/listinfo/rpg400-l or email: RPG400-L-request@xxxxxxxxxxxx Before posting, please take a moment to review the archives at http://archive.midrange.com/rpg400-l. _______________________________________________ This is the RPG programming on the AS400 / iSeries (RPG400-L) mailing list To post a message email: RPG400-L@xxxxxxxxxxxx To subscribe, unsubscribe, or change list options, visit: http://lists.midrange.com/mailman/listinfo/rpg400-l or email: RPG400-L-request@xxxxxxxxxxxx Before posting, please take a moment to review the archives at http://archive.midrange.com/rpg400-l. --- Incoming mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). 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Version: 6.0.541 / Virus Database: 335 - Release Date: 11/14/03 _______________________________________________ This is the RPG programming on the AS400 / iSeries (RPG400-L) mailing list To post a message email: RPG400-L@xxxxxxxxxxxx To subscribe, unsubscribe, or change list options, visit: http://lists.midrange.com/mailman/listinfo/rpg400-l or email: RPG400-L-request@xxxxxxxxxxxx Before posting, please take a moment to review the archives at http://archive.midrange.com/rpg400-l. _______________________________________________ This is the RPG programming on the AS400 / iSeries (RPG400-L) mailing list To post a message email: RPG400-L@xxxxxxxxxxxx To subscribe, unsubscribe, or change list options, visit: http://lists.midrange.com/mailman/listinfo/rpg400-l or email: RPG400-L-request@xxxxxxxxxxxx Before posting, please take a moment to review the archives at http://archive.midrange.com/rpg400-l. --- Incoming mail is certified Virus Free. 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