Re: Transitive Closure

"Laconic2" <laconic2_at_comcast.net> wrote in message news:4o6dndP5isL4WzXdRVn-vg_at_comcast.com...
>
> "Alfredo Novoa" <alfredo_at_ncs.es> wrote in message
> news:e4330f45.0405161549.7f66ece8_at_posting.google.com...
>
> > I prefer restriction. What selection does is a restriction.
>
>
> Interesting. The literature used to use the word "selection" until the
> early 1980s, when SQL became the de facto standard interface language.
At
> that point, the word "selection" began to be misinterpreted by people
> familiar with SQL, but not with relational operators. So the word
> "restriction" gradually displaced the word "selection".
>
> But it was simply to avoid confusion, rather than for any fundamental
> liguistic reason. Or so it seems to me.

It seems that way to me as well. The MV/PICK SELECT is just a restriction and not a projection at all (which it can do because the select is against a function, i.e. only the keys are returned for the qualified records).

The SQL SELECT started messing up the language from what I recall, in giving back a list/report with a projection as well. This is a pain in the neck when trying to teach PICK to SQL folks or vice versa. Saying "RESTRICT" intstead is so negative compared to SELECTing. --dawn Received on Mon May 17 2004 - 23:49:09 CEST