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From:Rick James Date:August 21 2012 11:30pm
Subject:RE: help with correlated subquery
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select  count(*), target_name_id, ep, avg(bottom), avg(averages)
    from  

        ( SELECT  avg(bottom) as averages, target_name_id as t,
                ep as e
            from  data_cst
            where  target_name_id = 44
            group by  target_name_id, ep, wafer_id) x,
        data_cst
    where  target_name_id = t
      and  ep = e
    group by  target_name_id, ep;

Please qualify all fields with table names (or aliases).  I can't tell what ep and e are.  Etc.

Please turn the "commajoin" into an explicit JOIN...ON.

> -----Original Message-----
> From: Larry Martell [mailto:larry.martell@stripped]
> Sent: Tuesday, August 21, 2012 3:35 PM
> To: mysql mailing list
> Subject: help with correlated subquery
> 
> I am trying to write a query that selects from both a correlated
> subquery and a table in the main query, and I'm having a lot of trouble
> getting the proper row count. I'm sure this is very simple, and I'm
> just missing it. I'll try and present a simple example. For this
> example, there are 27 rows, organized like this:
> 
> 
> mysql> select count(*), target_name_id, ep, wafer_id from data_cst
> where target_name_id = 44 group by target_name_id, ep, wafer_id;
> +----------+----------------+------+----------+
> | count(*) | target_name_id | ep   | wafer_id |
> +----------+----------------+------+----------+
> |        6 |             44 | 1,1  |       16 |
> |        3 |             44 | 1,1  |       17 |
> |        6 |             44 | 1,2  |       16 |
> |        3 |             44 | 1,2  |       17 |
> |        6 |             44 | 1,3  |       16 |
> |        3 |             44 | 1,3  |       17 |
> +----------+----------------+------+----------+
> 6 rows in set (0.00 sec)
> 
> I need to get an average of a column grouped by target_name_id, ep as
> well as the average of the averages grouped by target_name_id, ep,
> wafer_id, and I also need the count of the rows in the target_name_id,
> ep group. My query is getting the correct averages, but incorrect row
> counts:
> 
> mysql> select count(*), target_name_id, ep, avg(bottom), avg(averages)
> from (select avg(bottom) as averages, target_name_id as t, ep as e from
> data_cst where target_name_id = 44 group by target_name_id, ep,
> wafer_id) x, data_cst where target_name_id = t and ep = e group by
> target_name_id, ep;
> +----------+----------------+------+-------------+-----------------+
> | count(*) | target_name_id | ep   | avg(bottom) | avg(averages)   |
> +----------+----------------+------+-------------+-----------------+
> |       18 |             44 | 1,1  |  21.8056667 |  21.85458330000 |
> |       18 |             44 | 1,2  | 121.7984444 | 121.83983335000 |
> |       18 |             44 | 1,3  | 349.7634444 | 349.75016665000 |
> +----------+----------------+------+-------------+-----------------+
> 3 rows in set (0.01 sec)
> 
> The count for each row should be 9. What do I need in my count() to be
> counting the right thing?
> 
> 
> TIA!
> -larry
> 
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Thread
help with correlated subqueryLarry Martell21 Aug
  • RE: help with correlated subqueryRick James21 Aug
    • Re: help with correlated subqueryLarry Martell22 Aug
  • Re: help with correlated subqueryhsv22 Aug
    • Re: help with correlated subqueryLarry Martell22 Aug
      • RE: help with correlated subqueryRick James22 Aug
      • Re: help with correlated subqueryLarry Martell23 Aug
        • Re: help with correlated subqueryLarry Martell23 Aug
Re: help with correlated subqueryLarry Martell22 Aug
RE: help with correlated subqueryMartin Gainty22 Aug
  • Re: help with correlated subqueryShawn Green22 Aug
    • Re: JOIN, JOIN, JOINhsv23 Aug