Groups > microsoft.public.sqlserver.programming > #31272

Re: Unique Constraint Based on Dual GUID

Newsgroups	microsoft.public.sqlserver.programming
Date	2015-08-12 18:26 -0700
References	<mqbsbp$9va$1@dont-email.me>
Message-ID	<122678eb-cdfc-4e2b-82b6-e43945887545@googlegroups.com> (permalink)
Subject	Re: Unique Constraint Based on Dual GUID
From	--CELKO-- <jcelko212@earthlink.net>

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You missed my point! GUIDs are not for keys; they are locators for external global resources. This guy wants to use them for pointers like we did in the 1970'd network databases. 

If you use an actual compound key (a,b), then either they are drawn from two different domains that are independent (longitude, latitude), two different domains that are dependent (clothing size, colors), or the same domain (first color and second color). In the final case, the constraint (a < b) prevents (b,a), (a,a), and (b,b) Which means that the two-tone clothing item is only shown one way and really has two tones to it.

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Unique Constraint Based on Dual GUID Michael Cole <invalid@invalid.com> - 2015-08-11 14:07 +1000
  Re: Unique Constraint Based on Dual GUID Erland Sommarskog <esquel@sommarskog.se> - 2015-08-11 21:35 +0200
  Re: Unique Constraint Based on Dual GUID rpresser <rpresser@gmail.com> - 2015-08-11 12:46 -0700
  Re: Unique Constraint Based on Dual GUID --CELKO-- <jcelko212@earthlink.net> - 2015-08-11 15:30 -0700
    Re: Unique Constraint Based on Dual GUID rpresser <rpresser@gmail.com> - 2015-08-11 20:13 -0700
  Re: Unique Constraint Based on Dual GUID --CELKO-- <jcelko212@earthlink.net> - 2015-08-12 18:26 -0700
    Re: Unique Constraint Based on Dual GUID Michael Cole <invalid@invalid.com> - 2015-08-13 11:59 +1000

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