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From:Larry Martell Date:September 19 2012 6:36pm
Subject:Re: getting certain rows from a group by
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On Wed, Sep 19, 2012 at 12:04 AM,  <hsv@stripped> wrote:
>>>>> 2012/09/18 06:53 -0400, Larry Martell >>>>
> 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).
> <<<<<<<<
> There is a standard and ugly way of getting such a thing, but it entails repeating
> the table reference (supposing you want any, not every, to match):
>
> SELECT data_cst.target_name_id, image_measurer_id, nb, xb, vb, xt, bottom
> FROM (SELECT Min(bottom) AS nb, Max(bottom) AS xb, MIN(ABS(Avg(bottom) - bottom)) AS
> vb, Max(date_time) AS xt
> FROM data_cst
>       WHERE target_name_id IN (775, 776, 777, 778, 779, 780, 45, 44, 116, 117, 118,
> 119, 120, 121)
>       AND DATE(data_cst.date_time) = '2010-03-04'
>       GROUP BY target_name_id, ep, wafer_id
>       HAVING count(*) < 999) AS st
> JOIN data_cst ON st.target_name_id = data_cst.target_name_id AND (nb = bottom OR xb =
> bottom OR vb = bottom OR date_time = xt)

This:

MIN(ABS(Avg(bottom) - bottom))

Is not valid. It gives:

ERROR 1111 (HY000): Invalid use of group function

Which is why I was doing it with an order by. But I can figure out how
to work that into a join,

>
> One record will be returned for every row that holds a relevant extremum, not
> guaranteed to be unique.
>
> This query pertains only to your original subquery, not the whole query. To get the
> result to which you refer, join this to your original query, to which you have added
> something like vb:
>
> SELECT *
> FROM (original query) JOIN (this query) ON nb = minbottom AND xb = maxbottom AND xt =
> "Last Run" AND vb = .... AND (original query).target_name_id =
> (this_query).target_name_id
>
> --but I am not confident in the result. There are problems in the original query, the
> biggest that of avgbottom, stdbottom, maxbottom, minbottom none are aggregated over
> wafer_id. Therefore, it is not certain from which record from q1 they are returned. MySQL
> tends to pick the first that fits, but not only is nothing guaranteed, it is explicitly
> written that if such not aggregated fields appear, the output is not determinate unless
> all pertinent are equal, the possibility wherof the reason for allowing it.
>
> When that has been handled, it is needful to change the foregoing query to match that
> one in two levels, because averaging is not associative (there is also the problem of
> equality-testing on generated floating-point numbers). If it were only MAX and MIN, one
> level of not GROUPing BY wafer_id would be all right.
>
> By the way, in the original query, I suggest instead of
> data_cst.date_time BETWEEN '2010-03-04 00:00:00' AND
> '2010-03-04 23:59:59'
> this,
> DATE(data_cst.date_time) = '2010-03-04'
>
> Instead of
>
>      ... q1,
>      data_target
> WHERE data_target.id = target_name_id
>
> this would be better:
>
>      ... q1 JOIN data_target ON data_target.id = target_name_id
>
> I believe that
>      100-((SUM(numonep) - SUM(numbottoms))/SUM(numonep)*100)
>    = 100*SUM(numbottoms)/SUM(numonep)
> and
>      SUM(CASE WHEN reruns > 0 THEN reruns ELSE 0 END)
>    = SUM(GREATEST(reruns, 0))
>
>
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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