On 26/08/15 08:56, Adrian Klaver wrote:
On 08/25/2015 08:40 AM, Melvin Davidson wrote:
Adrian,
Stop being so technical. When we/I speak of natural keys, we are talking
about the column
that would NATURALly lend itself as the primary key.
Pretty sure this is a technical list:)
Don't let inconvenient facts get in the way of a good argument! :-)
[...]
Pretty sure parts are not unique to an exact vehicle, unless you are
talking a totally handmade one. They are not even unique to make and
model. As an example, I used to work on Class B Isuzu trucks. These
models(FTR) where also built for Chevrolet as the Forward models. So
right of the bat there where two part numbers for each part, one that
started with 9 if you got it from Chevrolet and one with 11 from
Isuzu, if memory serves. Then Isuzu decided to reorganize their part
numbers, so that introduced another number, all pointing to the exact
same part. Then there where those parts available from the parts
houses(NAPA, etc).
Then there was the greenhouse I worked for where we supplied UPC coded
tags for our customers. In the beginning, it was simple, the item
portion of the UPC was unique and with the company prefix served as a
'natural' key for the tags. Then the chain stores we worked with must
have all gone to the same seminar on how to be Walmart and decided
they did not want unique numbers, but UPCs tied to price groups that
covered a variety of plants. Luckily, I was too stupid to
Natural Stupidity??? :-)
(Sorry, couldn't resist!)
know surrogate keys where bad and had a sequence attached to the tag
table. This then became the tag id and made life a lot easier during
the transition. It still remains there, because people are people and
'natural' tends to be artificial and transient.
Extremely good examples, I'll bear them in mind - makes me even more
keen on surrogate primary keys. I'm always very wary when people tell
me some numbering scheme will NEVER change!!!
[...]
Cheers,
Gavin
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