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RE: [ProgSoc] Statistics from a database
Quoting Romney Lai <firstname.lastname@example.org>:
> maybe i am missing something here. cant you get the number of tow by a
> query like
> SELECT COUNT(*)
> FROM (SELECT DISTINCT tow FROM TOWS) ?
> If you can do that, you can calculate the mean/average fairly easily.
Yes, it's possible to determine the count 'n' of tows for any particular
grouping I chose, for instance, tows grouped by Location (a field of Tows),
using a query similar to the one you suggested. Note that this query only
examines the Tows table.
However, I'm not sure how to integrate this number 'n' into a query involving
the TowCounts table, since the rows to calculate 'n' may be missing after you
join the tables.
Can I do it using a sub-query?
I can get the data required to calculate the correct means, however, it
requires two queries: one to calculate 'n' and one to calculate the totals. The
results of the two queries then have to be combined manually. This is time-
consuming and error-prone.
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