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Re: A pk is *both* a physical and a logical object.

From: JOG <jog_at_cs.nott.ac.uk>
Date: Thu, 26 Jul 2007 03:23:35 -0700
Message-ID: <1185445415.561100.98380_at_o61g2000hsh.googlegroups.com> 






Just as another example of what i'm on about with this construct
m'larkey: Imagine the library has two copies of "harry potter and the
deathly hallows". Are they the same book?



    
  
  1.   If your construct is the one that uses the barcode on the sleeve as
an identifier, then no, different books.
  
  2.   If your construct is the one that uses the ISBN number as an
identifier, then yes, same book.






There's no correct answer, and which you pick just depends on the
application. A Loans database could use Barcodes; A library listings
database could use ISBN.
Received on Thu Jul 26 2007 - 12:23:35 CEST












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