From: | Andrew Gould <andrewgould(at)yahoo(dot)com> |
---|---|
To: | Peter Eisentraut <peter_e(at)gmx(dot)net> |
Cc: | postgresql <pgsql(at)symcom(dot)com>, Al Kirkus <Al(at)dist102(dot)k12(dot)il(dot)us>, pgsql-general(at)postgresql(dot)org |
Subject: | Re: Probably simple answer |
Date: | 2001-11-09 01:01:16 |
Message-ID: | 20011109010116.60146.qmail@web13404.mail.yahoo.com |
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Thread: | |
Lists: | pgsql-general |
Thanks. Sometimes there's just no getting around a
little work. :-)
Andrew Gould
--- Peter Eisentraut <peter_e(at)gmx(dot)net> wrote:
> Andrew Gould writes:
>
> > I think he simply wants the rows of the result set
> > numbered from 1 to whatever the last row is. This
> is
> > useful for referencing rows when discussing
> reports.
> > It is also an immense help when calculating a
> record's
> > statistical percentile ranking.
> >
> > Doing it in a table is no problem. But how do you
> > create one dynamically in a select query?
>
> It's not easily possible.
>
> Even if you were to write a server-side function
> that would implement such
> a counter, there is no guarantee that the rows would
> be returned in the
> order that the function is called in. (Depending on
> how you express the
> query it can be very likely, but there is no
> guarantee.)
>
> It gets worse if you use ORDER BY or DISTINCT. Then
> the problem amounts
> to adding a column to the result set after sorting,
> which is not possible
> in the SQL query model.
>
> So by far the easiest choice is to keep this counter
> in the client
> application as you loop through the result set.
>
> --
> Peter Eisentraut peter_e(at)gmx(dot)net
>
>
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