On Tue, Aug 21, 2012 at 8:26 PM, Larry Martell <larry.mart...@gmail.com> wrote: > On Tue, Aug 21, 2012 at 8:07 PM, <h...@tbbs.net> wrote: >>>>>> 2012/08/21 16:35 -0600, Larry Martell >>>> >> 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? >> <<<<<<<< >> Your trouble lys in the joining; in effect, you are joining a row with >> wafer_id 16 with a row with wafer_id 17, and also a row with wafer_id 17 >> with a row with wafer_id 16. >> >> A further advantage to using the now standard form of joining, as Rick James >> bids you do, is that one can add further conditions to it: >> >> select count(*), target_name_id, ep, avg(bottom), avg(averages) >> from (select avg(bottom) as averages, target_name_id, ep >> from data_cst >> where target_name_id = 44 >> group by target_name_id, ep, wafer_id) x >> JOIN data_cst >> ON target_name_id = x.target_name_id and ep = x.ep and wafer_id < x.wafer_id >> group by target_name_id, ep >> >> The inequality, maybe, will give you what you want. > > Not, wafer_id < x.wafer_id, but wafer_id = x.wafer_id - adding that > makes it work the way I want. Thanks!!
So now that I have this working, that have added another requirement. They also want a count of rows aggregated by a different set of columns. So I need to add another subquery, but I can't figure out how to get the row count. In this example query: mysql> select count(*) from data_cst where target_name_id=208082 and wafer_id=425845 group by target_name_id,wafer_id,lot_id,data_file_id; +----------+ | count(*) | +----------+ | 12 | | 12 | | 12 | | 12 | +----------+ 4 rows in set (0.00 sec) The result I need is 4 (i.e there were 4 distinct groups of target_name_id,wafer_id,lot_id,data_file_id). How can I get that? This will be a subquery, so I can't use mysql_num_rows() or FOUND_ROWS() after the fact. I need the result returned from the query. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql
