Primary Keys

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From: Rock (rockisland_at_yahoo.com)
Date: 10/20/04 

Date: Wed, 20 Oct 2004 11:02:58 -0600

I came across a database created by another person in the company that
frequently has 2 primary keys on its tables. I'm not sure why it was done
this way, my guess is to create uniqueness with the 2-field combination.

My question is: Is this poor design? Shouldn't we create constraints or
indexes if 2-field uniqueness is the purpose. Is one way more efficient
than the other? Any other thoughts as to why a table would be set up this
way? Thanks.

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