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From:Rick James Date:September 18 2012 8:01pm
Subject:RE: getting certain rows from a group by
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SELECT mn.*
       mx.*
> >    FROM ( SELECT @min = MIN(bottom),
> >                  @max = MAX(bottom), ... )
> >    JOIN data_cst mn  ON bottom = @min
> >    JOIN data_cst mx  ON bottom = @max

That is, the FROM finds the value for the desired row.
The JOIN then gets to the rest of the fields.
Caveat:  If two rows have bottom = @min, it returns both.


> -----Original Message-----
> From: Larry Martell [mailto:larry.martell@stripped]
> Sent: Tuesday, September 18, 2012 12:54 PM
> To: Rick James
> Cc: peter.brawley@stripped; mysql@strippedql.com
> Subject: Re: getting certain rows from a group by
> 
> On Tue, Sep 18, 2012 at 2:05 PM, Rick James <rjames@stripped>
> wrote:
> > For single query...
> >
> > Plan A:
> > Repeat the SELECT as once for each (MIN, AVG, etc) as a subquery in
> >    WHERE bottom = ( SELECT MIN(bottom) ... )
> >
> > Plan B:
> >    FROM ( SELECT @min = MIN(bottom),
> >                  @max = MAX(bottom), ... )
> >    JOIN data_cst mn  ON bottom = @min
> >    JOIN data_cst mx  ON bottom = @max
> 
> 
> Can you elaborate on this? I don't see how this will give me what I
> need. I'm not looking for the min or max bottom - I already have that
> - I'm looking for the row from each group that has the min and max
> bottom.
> 
> > Plan C:
> > Get rid of 3rd party packages that eventually get in your way instead
> of 'helping'.
> 
> It's not django that is getting in the way. django is a fantastic
> framework for web development. It's just changing requirements. The
> original developer (who no longer works here) created a few different
> classes, and then based on the original requirements, chose to use the
> one that supports a single query. That worked then, but may not work
> now. There are other classes that allow multiple queries, but then you
> have to parse the data and stuff it into the context that will be
> picked up by the browser yourself. The single query class does that for
> you. I may yet go that way, but I'm trying to avoid a big rewrite if I
> can.
> 
> >> -----Original Message-----
> >> From: Larry Martell [mailto:larry.martell@gmail.com]
> >> Sent: Tuesday, September 18, 2012 4:57 AM
> >> To: peter.brawley@stripped
> >> Cc: mysql@lists.mysql.com
> >> Subject: Re: getting certain rows from a group by
> >>
> >> On Tue, Sep 18, 2012 at 7:52 AM, Peter Brawley
> >> <peter.brawley@stripped> wrote:
> >> > On 2012-09-18 5:53 AM, Larry Martell wrote:
> >> >>
> >> >> I have this query:
> >> >>
> >> >> SELECT data_target.name as Target,
> >> >>         q1.ep as EP,
> >> >>         COUNT(*) as Wafers,
> >> >>         Lots,
> >> >>         SUM(numonep)/(COUNT(*)+SUM(CASE WHEN reruns > 0 THEN
> >> >> reruns ELSE 0 END)) as 'Sites/Wafer',
> >> >>         MAX(LastRun) as "Last Run",
> >> >>         SUM(CASE WHEN reruns > 0 THEN reruns ELSE 0 END) as
> Rerun,
> >> >>         COUNT(*)+SUM(CASE WHEN reruns > 0 THEN reruns ELSE 0 END)
> >> >> as
> >> Runs,
> >> >>         avgbottom as "Avg Bottom",
> >> >>         3*stdbottom as "3 Sig",
> >> >>         maxbottom as Max,
> >> >>         minbottom as Min,
> >> >>         SUM(numonep) as Count,
> >> >>         SUM(numonep) - SUM(numbottoms) as NAs,
> >> >>         100-((SUM(numonep) - SUM(numbottoms))/SUM(numonep)*100)
> as
> >> "%
> >> >> Success",
> >> >>         3*stdbottom/avgbottom as "3Sig/Avg",
> >> >>         AVG(avgbottom) as 'Wafer Avg',
> >> >>         AVG(Wafer3Sigma) as 'Wafer 3 Sigma',
> >> >>         AVG(Ranges) as 'Avg Range',
> >> >>         3*STD(Ranges) as '3Sig of Ranges',
> >> >>         MAX(Ranges) as 'Max Range',
> >> >>         MIN(Ranges) as 'Min Range',
> >> >>         (SUM(numonep) - SUM(numbottoms))/COUNT(*) as 'NAs/Wafer'
> >> >> FROM (SELECT target_name_id,
> >> >>               ep,
> >> >>               wafer_id,
> >> >>               COUNT(bottom) as numbottoms,
> >> >>               AVG(bottom) as avgbottom,
> >> >>               STD(bottom) as stdbottom,
> >> >>               MAX(bottom) as maxbottom,
> >> >>               MIN(bottom) as minbottom,
> >> >>               MAX(date_time) as "LastRun",
> >> >>               COUNT(*) as numonep,
> >> >>               COUNT(DISTINCT target_name_id, ep, lot_id,
> >> >> data_file_id)-1 as reruns,
> >> >>               COUNT(DISTINCT(lot_id)) as Lots,
> >> >>               3*STD(bottom) as Wafer3Sigma,
> >> >>               MAX(bottom) - MIN(bottom) as Ranges
> >> >>        FROM data_cst
> >> >>        WHERE target_name_id IN (775, 776, 777, 778, 779, 780, 45,
> >> 44,
> >> >> 116, 117, 118, 119, 120, 121)
> >> >>        AND data_cst.date_time BETWEEN '2010-03-04 00:00:00' AND
> >> >> '2010-03-04 23:59:59'
> >> >>        GROUP BY target_name_id, ep, wafer_id
> >> >>        HAVING count(*) < 999) q1,
> >> >>       data_target
> >> >> WHERE data_target.id = target_name_id GROUP BY q1.target_name_id,
> >> >> q1.ep;
> >> >>
> >> >>
> >> >> This works fine. But now I need to get a certain column
> >> >> (image_measurer_id) with each row returned that corresponds to
> the
> >> >> row from the group that has bottom = Min(bottom), bottom =
> >> >> Max(bottom), bottom closest to Avg(bottom), and bottom from the
> >> >> row where date_time = Max(date_time).
> >> >>
> >> >> Is this even possible from one query?
> >> >
> >> >
> >> > Might be, but what's the importance of doing it as one query?
> >>
> >> Because it's part of a django based web app, and the class that this
> >> is part of only supports having a single query. To use multiple
> >> queries will require a fairly major rewrite of the server side of
> that app.
> >>
> >> > I'd start by
> >> > saving this result to a temp table and developing the new query.
> >> > When that's running, see if you can to optimise a query built by
> >> > replacing the reference to the temp table with the original query.
> >>
> >> Thanks, I'll look into this.
Thread
getting certain rows from a group byLarry Martell18 Sep
  • Re: getting certain rows from a group byPeter Brawley18 Sep
    • Re: getting certain rows from a group byLarry Martell18 Sep
      • RE: getting certain rows from a group byRick James18 Sep
        • Re: getting certain rows from a group byLarry Martell18 Sep
          • RE: getting certain rows from a group byRick James18 Sep
            • Re: getting certain rows from a group byLarry Martell18 Sep
              • RE: getting certain rows from a group byRick James18 Sep
                • Re: getting certain rows from a group byLarry Martell19 Sep
                  • Re: getting certain rows from a group byLarry Martell19 Sep
                    • Re: getting certain rows from a group byLarry Martell19 Sep
                      • RE: getting certain rows from a group byRick James19 Sep
                        • Re: getting certain rows from a group byLarry Martell20 Sep
      • Re: getting certain rows from a group byLarry Martell18 Sep
  • Re: getting certain rows from a group byhsv19 Sep
    • Re: getting certain rows from a group byLarry Martell19 Sep
      • Re: getting certain rows from a group byLarry Martell19 Sep
    • Re: getting certain rows from a group byLarry Martell19 Sep
      • Re: getting certain rows from a group byhsv19 Sep