On Saturday, May 31, 2014 4:38:40 PM CEST, Axel Rau wrote:
Am 31.05.2014 um 13:56 schrieb Arnt Gulbrandsen
<[email protected]>:
If you declare it, then you're stuck with how that key
behaves. If it won’t increase in pairs,
Hmm, what do you mean with that?
A natural primary key is defined by something. That something defines
(parts of) its behaviour. It defines enough behaviour to make the column
into a natural primary key.
I've known definition which said "value must be a unique nonnegative
integer" which isn't terribly restrictive. You could use a step-by-two
sequence and meet that requirement. But I've also known one which said
"value must be supplied by remote service x".
Whatever it defines is defined. If you don't use it has a primary key, you
have a second column that's defined to act as if it were a primary key,
just without the keyword.
Arnt
