[thelist] MySQL Grouping problem
Joshua Olson
joshua at waetech.com
Mon Apr 11 16:32:53 CDT 2005
> -----Original Message-----
> From: Phil Turmel
> Sent: Monday, April 11, 2005 5:06 PM
>
> Richard/Joshua:
>
> MySQL has an example for this problem that addresses pre-4.1
> and current
> syntax (just max instead of min, adjust to suit):
>
> http://dev.mysql.com/doc/mysql/en/example-maximum-column-group
> -row.html
This solution, which uses temporary tables, is a viable solution. On a
similar note, this technique also can be used when creating high-speed
pagination across huge recordsets.
> As for fields in the select list that are neither aggregate
> nor grouped,
> MySQL extends the standard to pick ANY value from the grouped rows:
>
> http://dev.mysql.com/doc/mysql/en/group-by-hidden-fields.html
This was the oddity to which I was referring. We had a discussion about
this a few years back as well. Per the article:
"Do not use this feature if the columns you omit from the GROUP BY part are
not unique in the group! You get unpredictable results. "
Er, yeah, I can see why. That is why most most SQL implementations don't
allow for it. :-)
<><><><><><><><><><>
Joshua Olson
Web Application Engineer
WAE Tech Inc.
http://www.waetech.com/service_areas/
706.210.0168
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