Re: Surrogate primary key plus unique constraint vs. natural primary key: data integrity?
Date: Tue, 12 Mar 2013 16:26:12 +0000 (UTC)
Message-ID: <khnkv4$o4a$1_at_speranza.aioe.org>
Cimode wrote:
> All unique identifiers are at some point in time a surrogate key.
That is a truism. No identification exists in nature.
> Only designer's subjectivity qualify them as natural or primary key.
Maybe I mistake your point but you seem to suggest it is decided on a
whim. It is a consequence of defining the enterprise of interest. A
value assigned outside the enterprise of interest that is a key
within it is "natural".
A credit card number is a synthetic/surrogate key in the card issuer's
database but it's a natural key in the merchant's database.
I will quckly concede that "natural" key is a poor choice of
terminology. "Alien key" might be better, or "extant key". I'm sure we
> In the context of guaranteeing data integrity, I am still amazed at
Well when you work with bone-heads who actually ban natural keys from
being propagated as foreign keys, and who introduce a new surrogate in
every table, and in effect create link-lists of tables that you have
to navigate to do anything, you don't give in without a fight.
> how such implementation-driven minor point triggers so much debate.
-- RoyReceived on Tue Mar 12 2013 - 17:26:12 CET