Re: Fw: Is SQL silly as an RDBMS<->app interface?

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От Bruce Momjian
Тема Re: Fw: Is SQL silly as an RDBMS<->app interface?
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Msg-id 200307250035.h6P0ZGq18583@candle.pha.pa.us
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Ответ на Re: Fw: Is SQL silly as an RDBMS<->app interface?  (elein <elein@varlena.com>)
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Yes, it was more powerful because you could do aggregates in the query
independent of the results returned by the query.

The 'by' feature of aggregates always confused me because it would
modify the aggregate WHERE clause (that was independent of the outer
query) and restrict the aggregate to only process rows where the outer
query's column value matched the same column's value in the aggregate.

---------------------------------------------------------------------------

elein wrote:
> (Postquel, quel, whatever. My ingres days are showing.)
>
> Actually the aggregates made much more sense in [Post]quel
> than SQL.  The individual aggregate is qualified separately so that
> it does not mess with the entire query.  (Group by grief anyone?)
> Therefore it was able to select several different aggregates in one
> query. (But don't ask me to remember the syntax...)
>
> elein
>
>
> On Mon, Jul 21, 2003 at 03:57:33PM -0400, Bruce Momjian wrote:
> > Jan Wieck wrote:
> > > elein wrote:
> > > > Quel rules.
> > >
> > > PostQUEL ... we should have kept a compatibility mode for that.
> >
> > I prefer SQL for a few reasons:
> >
> >     nested queries
> >     aggregates that make sense
> >
> > Does anyone remember how QUEL had you put the qualifiction inside the
> > aggregate parens.  And the correlated aggregates were weird, sum(col1 by
> > col2 where col3 = ...).  It was a little subquery with a correlated
> > aggregate.  It still makes my head spin.
> >
> > --
> >   Bruce Momjian                        |  http://candle.pha.pa.us
> >   pgman@candle.pha.pa.us               |  (610) 359-1001
> >   +  If your life is a hard drive,     |  13 Roberts Road
> >   +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073
> >
>

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

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