On Tue, 2 Feb 2016 16:19:07 +0100 Yannick Duch?ne <yannick_duchene at yahoo.fr> wrote:
> There are also representations. Sometimes there is not really a > value, just an identity which is the only thing offering > sense/meaning, and what may be erroneously seen as a value is rather > a representation. Representation is all. The database -- the whole thing, front to back -- is just a model, an approximation of the real world. As designer, you decide how to model that world, the "enterprise of interest". You decide what "entities" there are, what properties they have, how they are known (identified). The DBMS knows nothing of what is being modelled. It's "just" a logic system. That logic operates on values. It doesn't distinguish between kinds of values, between natural and surrogate keys. That sort of thing contributes to the understandability (and hence utility) of the model, but they're extralogical: outside the theory. > All of this, using ID in place of *some* values???however at the cost > of more verbose queries Back in the real world -- the computing world, where there's an actual system implementing the math -- yes, some things are faster than others, and some allowances have to be made for the limitations of the implementation and the computer. :-) --jkl
