On 10/27/19 10:24 AM, Simon Slavin wrote: > On 27 Oct 2019, at 9:12am, Thomas Kurz <sqlite.2...@t-net.ruhr> wrote: > >> the discussion standard deviation has shown that at least STDEV and POWER >> would be very helpful if they part of SQLite core. > These are presentation issues. Not database issues. The results of such > calculations are unlikely to be used to decide on the continuation of a SQL > statement.
Doing a group by summary query to get the mean and stdev of a sample in the database, and then using those to construct a where clause to get/exclude data points that are outliers would seem to be a very reasonable sort of query that is really a database issue. This could normally be done as two distinct queries (maybe within a read transaction so we get consistent data) and the stdev and mean built by building a count of records, and the sum of the value and value**2, and computing the mean and stdev from that in code, as was shown earlier in the thread, but having STDEV as a built-in summary function could be useful. -- Richard Damon _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
