SQLwaterheadretard3 (Was: Is it just me, or is Sqlite3 goofy?)

[Ben Sizer]

Bryan Olson wrote:
> Ben Sizer wrote:
> > It's not a crackpot theory. It's a completely reasonable theory. SQL is
> > based on relational algebra, which provides a mathematical set of
> > operators for grouping data that is stored in separate sets. That data
> > is selected and projected according to its value, and nothing else. The
> > concept of it having a 'type' has been overlaid on top of this,
> > presumably to facilitate efficient implementation, which tends to
> > require fixed-width rows (and hence columns). It's not necessary in any
> > sense, and it's reasonable to argue that if it was trivial to implement
> > variable width columns as efficiently as fixed width columns, that
> > explicit data types might never have needed to exist.
>
> The mathematical definition of the relational model includes
> that data values are drawn from specific sets.

Well, I did say relational algebra, which from what I understand
predates the official 'relational model'.

> Implementing variable width columns has nothing to do with it.

On a practical level, it has lots to do with it!

> Here's
> the reference:
>
>     1.3. A Relational View of Data
>
>     The term relation is used here in its accepted mathematical
>     sense. Given sets S1, S2, ···, Sn, (not necessarily
>     distinct), R is a relation on these n sets if it is a set
>     of n-tuples each of which has its first element from S1,
>     its second element from S2, and so on [1]. We shall refer to
>     Sj as the jth domain of R.

Does it specify anywhere that sets S1...Sn cannot each be the universal
set? To put it another way - although the spec implies the existence of
limited set domains, and data types enforce limited domains, I don't
think a requirement to allow limited domains is a requirement for
static data types.

-- 
Ben Sizer