On Fri, 12 Oct 2018 08:27:10 +0200 Clemens Ladisch <clem...@ladisch.de> wrote:
> John Found wrote: > > i.e. how to select only the groups that contain > > some value in the set of values in a column not > > specified in group by clause. > > > > select > > (select group_concat(b) from t t1 where t1.a = t2.a) as list > > from t t2 > > where b = ?1; > > Similarly: > > select > group_concat(b) as list > from t > where a in (select a > from t > where b = ?1) > group by a; > > But you will not be able to avoid the subquery: the filter has to > include all other rows of the group with matching b, and after the > group_concat(), the result is no longer in a form useful for lookups. > (And doing the filter after the grouping is probably not efficient.) Hm, is sounds strange because when HAVING clause is processed, the aggregate functions should not be processed yet (for a performance reasons) i.e. the query still has access to all values from the field b and theoretically should be able to search these values the same way it searches them on executing min() or max() aggregate functions. > > > Regards, > Clemens > _______________________________________________ > sqlite-users mailing list > sqlite-users@mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users -- John Found <johnfo...@asm32.info> _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
